Castor oil??? I need something cleared up...

I have often been told by people that we dont need castor oil in our fuel anymore. I have been told that the lubrication abilities of the newer synthetics is better than castor. I think this may be true. But I have always believed, and been told, that Castor carried the heat out of the motor better than Synthetics. Am I correct here? Is the ability of the castor to carry the heat out of the engine better than that of the synthetics? Is this one of the main reasons we need a portion of castor in our fuels?

If this true then no wonder Brad and I have been banging out heads into the wall trying to fight the burn down effect on the 4s. You have a motor that runs best on Synthetic but it heats up very easily when the ambient temps are up and it is in a venturi setup. Yet it performs best with a venturi setup on all Synthetics. Missing a needle can hurt a little. When we try to run Castor blends in the 4s there is an immediate RPM loss and a noticable power loss in the overall engine performance. It still works but not like a perfect needle on Sythentics.

My question is does Castor carry the heat away better than the Synthetics? And is that why we need castor blended fuels?

Thanks in advance.

LAST EDITED ON Dec-17-03 AT 00:27 AM (CST)
 
Yeah, And if we run caster to carry the heat away, why do we run up to 29% oil. It's my understanding that the more oil you run in 2 strokes the slower the burn, the slower the burn the hotter the engine runs ????.

Maybe with a 4 stroke, it's just an issue of not enough heat to keep the glowplug hot during all the non-firing strokes. The synthetic burns and should run hotter because of that...more stuff burning.

When I mixed speed fuel, I found that 65% nitro ran the same rpm with 15%, 20% or 25% synthetic (UCON). I would suggest trying UCON instead of Klotz. We thought it was pretty good stuff, but castor wasn't in the cards with such high nitro...wouldn't stay mixed, and Klotz was years in the future. I did find that some of the fuel mixers can get UCON for you, Morgan, I think. UCON is/was "Union Carbide", who sold out to Dow Chemical after the disaster in India. Below is an article that GMA had on his website, but I got it off RCO (I think). Steve

Stunters: There is still a lot of controversy on castor-vs-synthetic. Searching the archives I found no "tech notes". The following castor article was done by an obviously good researcher. Good reading for bean-heads. George Aldrich comments at the end of the article.
P.
********************************************
CASTOR OIL
By Bert Striegler, picked from George M. Aldrich's web site, now closed down.
Back in 1983 there was quite a controversy in Radio Control Modeler magazine about the tests that were necessary to measure the "lubricity" of various oils that might be useful in model engines. Castor oil was used as the benchmark, but it was obvious no one knew why this was so. They apparently got a lot of info on various industry tests of lubricants, but these were really designed for other purposes. This was my answer. I will remind you that I was a lubrication engineer and not a chemist, but I drew my chemical info from Bob Durr, the most experienced lubricant scientist in the labs at Conoco. Bob worked with my group on many product development projects and I can tell you that he is one smart hombre! Small changes were made in the text, but surprisingly very little has really changed since this was originally written. Here goes with the answer:
"I thought I would answer your plea for more information on castor oil and its "film strength", which can be a very misleading term. I have never really seen a satisfactory way to measure the film strength of an oil like castor oil. We routinely use tests like the Falex test, the Timken test or the Shell 4-ball test, but these are primarily designed to measure the effect of chemical extreme pressure agents such as used in gear oils. These "EP" agents have no function in an IC engine, particularly the two-stroke model engine types.
You really have to go back to the basics of lubrication to get a better handle on what happens in a model engine. For any fluid to act as a lubricant, it must first be "polar" enough to wet the moving surfaces. Next, it must have a high resistance to surface boiling and vaporization at the temperatures encountered. Ideally the fluid should have "oiliness", which is difficult to measure but generally requires a rather large molecular structure. Even water can be a good lubricant under the right conditions.
Castor oil meets these rather simple requirements in an engine, with only one really severe drawback in that it is thermally unstable. This unusual instability is the thing that lets castor oil lubricate at temperatures well beyond those at which most synthetics will work. Castor oil is roughly 87% triglyceride ricinoleic acid, which is unique because there is a double bond in the 9th position and a hydroxyl in the 11th position. As the temperature goes up, it loses one molecule of water and becomes a "drying" oil. Castor oil has excellent storage stability at room temperatures, but it polymerizes rapidly as the temperature goes up. As it polymerizes, it forms ever-heavier "oils" that are rich in esters. These esters do not even begin to decompose until the temperature hits about 650 degrees F. Castor oil forms huge molecular structures at these elevated temperatures - in other words, as the temperature goes up, the castor oil exposed to these temperatures responds by becoming an even better lubricant!
Unfortunately, the end byproduct of this process is what we refer to as "varnish." So, you can't have everything, but you can come close by running a mixture of castor oil with polyalkylene glycol like Union Carbide's UCON, or their MA 731. This mixture has some synergistic properties, or better properties than either product had alone. As an interesting sidelight, castor oil can be stabilized to a degree by the addition of Vitamin E (Tocopherol) in small quantities, but if you make it too stable it would no longer offer the unusual high temperature protection that it did before.
Castor oil is not normally soluble in ordinary petroleum oils, but if you polymerize it for several hours at 300 degrees F, the polymerized oil becomes soluble. Hydrogenation achieves somewhat the same effect.
Castor oil has other unique properties. It is highly polar and has a great affinity for metal surfaces. It has a flash point of only 445 degrees F, but its fire point is about 840 degrees F! This is very unusual behavior if you consider that polyalkylene glycols flash at about 350-400 degrees F and have a fire point of only about 550 degrees F, or slightly higher. Nearly all of the common synthetics that we use burn in the combustion chamber if you get off too lean. Castor oil does not, because it is busily forming more and more complex polymers as the temperature goes up. Most synthetics boil on the cylinder walls at temperatures slightly above their flash point. The same activity can take place in the wrist pin area, depending on engine design.
Synthetics also have another interesting feature - they would like to return to the materials from which they were made, usually things like ethylene oxide, complex alcohols, or other less suitable lubricants. This happens very rapidly when a critical temperature is reached. We call this phenomena "unzippering" for obvious reasons. So, you have a choice. Run the engine too lean and it gets too hot. The synthetic burns or simply vaporizes, but castor oil decomposes into a soft varnish and a series of ester groups that still have powerful lubricity. Good reason for a mix of the two lubricants!
In spite of all this, the synthetics are still excellent lubricants if you know their limitations and work within those limits. Used properly, engine life will be good with either product. Cooked on a lean run, castor oil will win every time. A mix of the two can give the best of both worlds. Most glo engines can get by with only a little castor oil in the oil mix, but diesels, with their higher cooling loads and heavier wrist pin pressures, thrive on more castor oil in the mix.
Like most things in this old life, lubricants are always a compromise of good and bad properties. We can and do get away with murder in our glo engines because they are "alcohol cooled" to a large degree. Diesels, though, can really stress the synthetics we use today and do better with a generous amount of castor oil in the lubricant mix. Synthetics yield a clean engine, while castor oil yields a dirty engine, but at least now you know why! "
Bert Striegler
Bert was the Sr. Research Eng'r. (ret.) at Conoco Oil Co. He's a graduate in aeronautical eng'rg., and a long time modeler. I never understood how he wound up in the oil research business, but I guess it's because he's just very smart ! I deserve no credit, Bert's the brain ! /George M. Aldrich

I have found no need for Castor in the engines I run for the way I run them. Castor seems to have 3 things that stunt can use. It helps to build up where the metal is wearing, leaves an anti rust protection in the engine when not in use and it helps the 4-2-4 transition quicker. All other aspects of Castor only come into play when you are to lean. With AAC technology we are not even seeing anywhere near the damage we used to from ABC and iron/steel. When AAC gets lean it simply expands away from the piston and after cool down returns. This is for everything but a complete burn down, which I never see in Stunt. Not to say it does not happen but I have not seen it since I came back to control line. I hate burned on Castor so much that I would rather replace parts ever so often rather than run it. I also never oil my engines after flying. We die dry and this is enough to get all of the raw fuel out. It does not hurt to oil but I fly enough that it is not needed. If you are not flying for long periods I highly recommend you oil between flying sessions.
Richard Oliver

Common wisdom in Combat circles is that some castor in the fuel will help protect the engine when you have a lean run.

Henry Nelson uses straight UCON oil in his, however (he wrote about running Nelsons in MACA Newsletter some time ago). Helicopter guys hate castor (but then again, they can always land and reset the needle). With the new ABC/AAC BB motors, I suppose you don't really need castor, but maybe it does help when you have a lean run and can't shut down..

Since I am using both older traditional baffle motors with steel liner plus ABC Schneurle designs in a typical flying session, and...

I don't want to haul two different types of fuel to the flying field...

my fuel mixture (25% oil, and this is c. 60% castor, 40% syn) is paced to the worst case condition, namely protecting the baffle engines. And, by the way, the ABC ones run just fine on this mix.

I agree that Castor does not hurt and the engines will run fine with your mix. I can remember in FAI pylon where we were required to run 20% Castor only and after a 5 heat day we would disassemble our engines and scrub with wire brushes to get the varnish out of the liner for the next days racing, which was causing a power loss. This is because of the tight fits and is in no way applicable to old technology. Don Nix used to put Castor (1-2%) in Power Master fuel even when we demanded all synthetic. He would tell us you need just a little. Can't say it hurt but it still left the burnt on Castor stains and I hated it. In my Ro-Jett blend I have them put in 5% Castor just for the insurance but for my personal engines I run 22% all syn.
Richard Oliver

The heli guys don't like castor because of the varnish. And they do tend to run their engines rich, like Stunt people do.

Doug,

The thread seems to have wandered a bit from your direct question about carrying heat out of the engine...

In Bert Striegler's long monograph, however, he points out the answer: Castor doesn't burn or vaporize away in the combustion chamber.

For cast iron pistons in steel sleeves, the dreaded varnish actually helps by filling the porosity with a sort of lube. Apparently, iron in steel isn't/wasn't machined to the tight specs of AAC or ABC modern engines, so the light varnish thickness lubes and helps the old metals.

Newer processes and materials allow tighter fits, more controlled expansion clearances and other performance enhancing benefits like the triple bypasses in most schneurle engines. There's no need for a layer of varnish to take up clearances, and there's NO ROOM for it.

Castor at higher heat becomes a thicker lube, and as it isn't likely to burn carries heat out of the engine when it is ejected through the exhaust. The varnish layer helps porous cast iron pistons keep seal for longer life. Most synthetics are excellent detergents, but for iron/steel, detergency is NOT desirable. It cleans that "dynamic gasket" layer off, widening clearances and giving the impression of lost 'compression.'

For ABC or AAC, the designed-in tight clearances have no room for a varnish build-up. Detergency IS desirable: it keeps the metals clean, and better able to maintain the designed and manufactured clearances.

So, yes, castor heats up, does not burn away, and carries the heat it picked up out of the engine, but for modern process engines, the varnish problem is more important.

IMHO, anyway, so as not to offend <G>

I have bought a number of engines (R/C) off e-bay and at collecto's that when I took the backplate off the bearings, crankshaft, were a mass of rust,and the bearings had to be replaced.

I have bought older engines, steel sleeve, iron piston that the wristpin was rusted so tight into the piston it couldn't be removed.

Engines that I have purchased that were ran with caster or part caster fuel have not had these problems.

I am a firm believer in caster oil in all my engines. To the average R/C guy, TT-pro's OS-FP's or F's,Magnum's older Tigers, especially those engines sized 40 and below are throw away engines they must think that way or they wouldn't use fuel with 18% or less oil(and none caster). One of our local hobby shops will not even carry plain bearing engines as he considers them junk, he also advocates not using any caster oil in his fuels that he mixes.
Engines are expensive,and I try to keep them as long as possible, without replacing any more parts than is necessary. Caster works for me.

Hothandle

What you are saying is that on a 4stroke the needle valve range seems to be to narrow between just right, too rich, and dying too lean. On a 2 stroke playing with the oil percentage and other ingredients can broaden the needle range. It sounds like that doesn't work on the 4s. Have you tried using a finer needlevalve assembly. Combat has had a similar problem in combat with high pressure bladders for years. The solution is a small, fine thread needle valve- the OS 1a. It is the only one we've found with .35mm pitch threads.

You might try using one. It may need to have the holes opened up slightly so it can flow more fuel at the low suction pressures in a 4s. If that isn't enough, you can chuck the needle in a lathe and grind a finer taper on the needle in the working range. Stock taper is about 7 deg. That can be changed to 3 deg. or even 1 deg. the OS is real handy for this. When you get the taper right the needle can be pressed further into the holder to get it to shut off.

LAST EDITED ON Dec-17-03 AT 03:01 PM (CST)
 
>What you are saying is that on a 4stroke the needle valve
>range seems to be to narrow between just right, too rich,
>and dying too lean. On a 2 stroke playing with the oil
>percentage and other ingredients can broaden the needle
>range. It sounds like that doesn't work on the 4s.

It does work, just in the opposite direction. More highly viscous oil makes the needle worse. Lower viscosity oils make the needle better. I feel this is simply due to fuel draw issues and not combustion issues. There seems to be little benefit from overcooling a 4 cycle, but overheating one is just as bad or worse.

I really don't think there is much difference from running a 4 cycle and running a 2 stroke engine in a 2-2 break.

Brad,
The only reason I am bringing this thread up is due to me thoughts about how castor transfers heat better. These guys here say it works better in a lean condition. Well when you are really honking the 4s it is at a pretty lean setting right? Very little smoke when the props are small and the RPMs are high. Just another little thing I was thinking about. But castor in a 4s is not a good option around here. So we will keep hunting....

>Brad,
>The only reason I am bringing this thread up is due to me
>thoughts about how castor transfers heat better. These guys
>here say it works better in a lean condition. Well when you
>are really honking the 4s it is at a pretty lean setting
>right? Very little smoke when the props are small and the
>RPMs are high. Just another little thing I was thinking
>about. But castor in a 4s is not a good option around here.
> So we will keep hunting....

I think the answer is just keep the stupid thing from going lean in the first place!!!!

I do not think a smidge of castor would be a bad thing. I am just not sure there is a benefit as is so plainly seen in the case of the 2-stroke. In the case of the 2-stroke the goal is to actually overcool the combustion chamber slightly to promote the misfire we commonly call a "4 stroking mode". In the 4 cycle, rich misfiring is not a good thing. Even though running slightly on the rich side is nice (not enough to promote misfires). I like to see the engine smoking lightly if possible. The most probable way to promote this, however, is in the fuel delivery and the mixture itself, not by changing the fuel.

Running a 4 cycle on a suction system is simply no different than running a 2 stroke in a 4 stroking mode. It is nice if you plan for the "boost" associated with the verticals, as the mixture changes ineveviably from rich to lean. This is the same problem that plagues the high pitch 4-2 break 2 strokes. There simply is far less governing with this method as there is with the lower pitch "back side of the curve" type run.

The very interesting thing is that the fuel consumption seems to go down in the higher RPM mode no matter how effectively the fuel is delivered to engine. Also it seems to use less fuel irregardless of the size of the throttle opening. The ability to "force" the engine to run slightly rich seems to go away at the higher RPM's also. This is very perplexing.

This has forced me to say that I have "hit the wall" on the effectiveness of the Saito in high RPM mode. It simply has nothing to do with the ability to pull the RPM, but instead the problem lies in the LACK of fuel consumption. At some point the engine is lean for whatever reason at the higher RPM's. This is in stark constrast to the "loaded" run that I used for the last 2 years which always forced a slightly rich run.

Funny thing is the engine is LEANER in high RPM mode, but properly excecuted, I am not sure it is HOTTER than the more loaded run. The horrible double cross is the OVERHEATED/LEAN combination. I simply do not trust this combination even though the "burndown" is a lovely speed regulator.

The future goal is to be just slightly rich but keep the mixture constant in all points of the hemisphere. This slightly richer setting may require a bit more pitch to compensate.

Only time and testing will tell now....

Exacto mundo my friend.

Funny thing is when you run the motor in the leaner low pitch setup it is actually cooler to the touch upon landing. Breathes better I guess.

Man we have learned alot!!... But then again the more I learn the less I know....

>Exacto mundo my friend.
>
>Funny thing is when you run the motor in the leaner low
>pitch setup it is actually cooler to the touch upon landing.
> Breathes better I guess.
>
>Man we have learned alot!!... But then again the more I
>learn the less I know....

The engine heats up less, because you have less load on it. Start a cold car engine, drive a flat road at low throttle settings, ease along. Takes a long time to warm up. If you started that cold engine at the bottom of a 15 mile, 6% grade (try to imagine it, we got some), it would be warmed up pronto!

If fuel viscosity is an issue with fuel draw, you could prove that by opening up the cross hole in the spraybar by .005" or so. Alternately, you might use the low viscosity synthetic oil with some castor, to bring the visc. index back to the norm. It still seems to me that the castor might be cooling the glowplug too much. You might try an onboard glow driver, to check that theory. If you have 5% castor and 15% Klotz, the detergent action of the Klotz will keep the castor from mucking up your engine just fine. There's 3 things to try. Steve

>The engine heats up less, because you have less load on it.
>Start a cold car engine, drive a flat road at low throttle
>settings, ease along. Takes a long time to warm up. If you
>started that cold engine at the bottom of a 15 mile, 6%
>grade (try to imagine it, we got some), it would be warmed
>up pronto!

Good example. I would say this is what we have found. The underloaded 4 cycle over though it is slightly leaner it is still cooler.

>If fuel viscosity is an issue with fuel draw, you could
>prove that by opening up the cross hole in the spraybar by
>.005" or so.

Huh... that might be an idea...

>>If fuel viscosity is an issue with fuel draw, you could
>>prove that by opening up the cross hole in the spraybar by
>>.005" or so.
>
>Huh... that might be an idea...

If you can already open the needle valve and get the engine too rich, then opening the cross hole is going to be of no value. You are already restricting its size by closing the needle, and if you make it too big then you are going to make adjustment of the needle difficult. Besides, it is better to have a (smaller) round hole open than a (larger) round hole nearly closed with just a slit around the outside that is open.

Well, if the needle valve adjustment range is very narrow, and the engine tends to lean out in maneuvers, my guess, as I've said before, is that you're simply using too big a venturi. If using a smaller venturi results in more than an acceptable drop-off in power, then the answer is obvious - a pressure fuel system. Varying the amount of oil in the fuel, or going to a finer needle, will simply allow you to ignore the problem, until one day, it bites..

>
>>>If fuel viscosity is an issue with fuel draw, you could
>>>prove that by opening up the cross hole in the spraybar by
>>>.005" or so.
>>
>>Huh... that might be an idea...
>
>
You are already restricting its size by closing the
>needle, and if you make it too big then you are going to
>make adjustment of the needle difficult. Besides, it is
>better to have a (smaller) round hole open than a (larger)
>round hole nearly closed with just a slit around the outside
>that is open.

Leonard,
Only in an improperly designed needle valve assembly would the needle alter the size of the jet, or hole in the surface of the spraybar.
The fuel should be metered by the position of the needle in the spraybar seat and there should be a clear and unobstructed path from the seat to the jet.

>If you can already open the needle valve and get the engine
>too rich, then opening the cross hole is going to be of no benefit.

This is correct, but not related to the metering of the fuel.

regards

A Stunt engine runs at a lower RPM than a Combat engine. The lower RPM stunt engine can live with the low 16% oil but the high RPM combat engine does not like 16% oil. I have several OS Max 25 LA engines 2 on my stunt airplanes and they run fine on the 16% oil type fuel that I buy at the local hobby shop. The same OS Max 25 LA engine running at a higher RPM on F2D combat airplanes does not like the 16% fuel. The F2D combat engines over heats and starts to run strange. I can tinker with the needle and usually fix the problem after about 3 runs by setting the needle slightly rich. I started adding caster oil to the fuel for a total of 20% oil and I no longer have a problem with F2D combat airplanes the engines run perfect every time. I don't like having 2 mixtures of fuel so now I mix all my fuel 20% oil. The stunt engines don't seem to mind the extra oil I think the needle is easier to adjust. Add 6.7 ounces of caster oil to Fuel with 16% oil to get 20% oil.

Help me out here.
I see in the posts, several different posts about Speed and R/C engines. AND then Richard say’s he doesn’t like castor at all. Were you talking JUST about the RO JETT ENGINES?

Original post was about Four Strokes heat transfer.
Have you checked with an IR gun or thermo stick of what a Four Stroke temperature is at the Head,the exhaust and the case? Have you checked it RUNNING with different oils and fuels?

Build up is the by-product of any combustion engine. It Happens.
MR.ALDRICH told me once. If you have an engine that needs cleaning (remove the build up) use less Castor next time. HOWEVER, ALL engines should have at least 18% all castor oil to preserve the engine in case of a high heat run.

DISCLAMER:
I know NOTHING about Four Strokes (model engine).
So any help to put me on the same page will be helpful

Scott(Knowlage)Riese

Doug

Maybe this has already been said but my theory is synthetic is a great lubricant and a poor coolant; castor is a great coolant but a poor lubricant. By running a mix you get the best of both worlds. Granted the Fox 35 is an exception because it is so thinned skinned and needs lots of castor to cool it. I run up to 40% synthetic in my own Fox's but I don't fear the lean run. I recommend all castor to my customers to protect the motor.

I've read in this thread that we don't need castor, if castor is so bad why does OS still recommend all castor in there LA's

Larry

Larry, OS as well as Cox and several others used this as a way to prevent engine damage and warranty claims. Castor is insurance against the really lean run. I do not know how much testing any of the thread contributors have done but we have done a lot. The bottom line as far as a burn down is the temp goes way past the safety range in any case for all oils and the damage is done no matter what oil is used. Even with the 100 degrees of extra protection that Castor will provide in almost all cases you will shoot right by this mark in a burn down. Now as for cooling properties Castor does run cooler, some, and in tight cowls and on hot days it might be perceived as good. As for needing it I have stated for my engines it is not needed but does not hurt, in small quantities, but I personally do not like the residue and have never had a burn down either. One way to think of castor is if it is leaving all this burned on residue on the out side of the engine what is it leaving on the inside?
I also do not recommend that my customers use all synthetic for the same reason OS does, insurance. I also know if you fly a lot you are going to have build up and power loss over time and will need to replace some parts due to this build up. Modern metallurgy and machining tolerances do not allow for the build up. The four strokes can not stand the build up in all the moving parts, especially the valves, and they do not recommend it for the same reason that OS does. To ward off warranty claims. The best way to tune for chamber temps is the heat range of the glow plug. Part of the 4S heat is the need for a really hot plug to keep the fire lit every other stroke. This is hard to do with a cold plug which helps keep the engine cooler by not burning all the fuel and using this unburned fuel as a coolant. It is a balancing act for sure and the system is at play here and not a single ingredient such as oil.
Richard Oliver

>One way to think of castor is if it is leaving all this burned on residue on the out side of the engine what is it leaving on the inside?

On the inside you have fresh fuel and oil running threw the motor nothing standing still, I would think that since there is 8000 to 11000 intake strokes a minute. The castor on the outside is attached threw out the flight and has plenty of time to bake on.

One thing I would let people know is if you have been running castor for a long time in your engine DO NOT CHANGE.

I've never run your motors so I can't agree with you on this one, though I do respect your opinion and comments. I run Aero Motors and Randy recommends Castor. I've been running his motors since 1986 and not one engine has ever gone south. I have one OS46 VF that’s been in two planes and is now in a third with over 2500 flights on it. Still running strong and it has had the Aero AAC in it since it was new.

Granted the Fox 35 is a different beast but I have spent many hours of testing different fuels and the two best things I’ve found are Castor and Aero1 Additive.

As you say Castor is there for warranty purposes, nobody likes insurance but we buy it. Why not on our model engines too.

Larry

>Doug
>
>Maybe this has already been said but my theory is synthetic
>is a great lubricant and a poor coolant; castor is a great
>coolant but a poor lubricant. By running a mix you get the
>best of both worlds. Granted the Fox 35 is an exception
>because it is so thinned skinned and needs lots of castor to
>cool it. I run up to 40% synthetic in my own Fox's but I
>don't fear the lean run. I recommend all castor to my
>customers to protect the motor.
>
>I've read in this thread that we don't need castor, if
>castor is so bad why does OS still recommend all castor in
>there LA's
>
>Larry

Actually, I think it should be said that some (not all) synthetic oils are great lubricants, but none are as great at cooling for our purposes as is castor. (This is a non-issue on a water cooled 4-stroke engine like our automobile.) And if the engine gets too hot, the synthetic oil that is mixed with the fuel as with our engines will simply burn up in the combustion process leaving you with no lubricant.

Synthetic oil is not as messy to clean off of the airplane because some (much, most) of it will burn in the combustion process, and there will be none left to leave with the exhaust. Remember, it is hot in the combustion chamber. Synthetic oil also makes for a cleaner exhaust for a pipe engine and does not contribute to the pipe's carboning up. Oh, and the engine looks nice and shiny new on the outside as well.

Castor is a great lubricant and a better coolant than most, if not all synthetics. And if it gets too hot it will become an even better lubricant and protector of the engine. However, it will leave a messy residue on both the inside (protectant) and outside (looks ugly) of the engine. It is also messier to clean off because nearly all of it will do its job and leave with the exhaust. Call it what you will, but it is the price of having protection. If there is no, or very little oil to clean off of your airplane, ask yourself the question, "What is happening inside of my engine?" There had better be some spilling out, or those little specs you see will be pieces of your engine.

Generally an ABC engine with a ball bearing supported crank can get by with less castor. A plain bearing engine should have at least 50% castor, and if it is an iron piston engine, then using all castor would be the preferred (sometimes mandatory) lubricant.

However, using all castor could prove to be detrimental to ball bearing engines if you do not run them a lot or do not use after run oil when you store them, as the bearings could gum up and then slide instead of roll which would then destroy the engine. If you run them a lot, this is probably a non-issue.

In the same vein, using all synthetic in ball bearing engines can also prove detrimental if you do not run them a lot or use after run oil when you store them (for even shorter lengths of time), as the bearings can rust and then do many funny things which will also destroy the engine. Note: rusting of the bearings can happen in a shorter period of time than the gumming up of the bearings from the use of castor. And it is not just fuel residue that causes this. Some synthetic oils actually contribute to the rusting. Oh, and don't expect that a couple of drops of after run oil squirted into the intake wll coat every last portion of the bearings, either. Most of it probably won't even get that far.

For my part, I will use a 50-50 blend in my ball bearing, ABC (or AAC) engines, and all castor in my plain bearing engines--even those that are ABC or ABN. I may have to clean the engines occasionally when I use all or part castor. And on the pipe engines we have found that you need to keep a check on the pipe and header and clean these internally occasionally, too. But then, I have to wash my car every so often when I drive it, as well. It is the price we pay for using our equipment.

>
>Actually, I think it should be said that some (not all)
>synthetic oils are great lubricants, but none are as great
>at cooling for our purposes as is castor.

I would not bet the house on that. In the 4 cycles, nothing I have tried cools better than Powermaster YS 20/20, including Sig Champion and Powermaster GMA blends both containing 50% castor.

I am not convinced the synthetics do not have equal cooling power. I am also not convinced that a large percentage of the oil expelled (and not burned) from Doug's, Bob's, and Mike's PA's is not Klotz. The oil is very red.

I think modelers started with castor years ago becasue it was cheap, readily available, and the engines could be made cheaper with softer materials because of the natural varnishing action of the castor.

I have dared Doug to start a PA 65 on all synthetic and never switch. He won't do it. He does not have the $300 to bet on it, and the Sig fuel works fine. So why bother?

I do love the fact that Richard is OK with 100% synthetic fuels. I have found no benefit to castor in my fuels that cannot be surpassed by some synthetic.

All in all, I think the biggest maistake is to lump all synthetics into one catagory. The main advantage to synthetic oils is that they are availabe in several different formulations and viscosities. There are several other synthetic oils out there except UCON and Klotz. Too bad most do not mix with methanol....

LAST EDITED ON Dec-18-03 AT 10:35 AM (CST)
 
Well said Leonard

Larry

I think I am not articulating my point as well as I would like. I do not like Castor and never ran it in 28 years of racing. If I had thought that Crisco would help in going faster or making more power I would have used it. I have run 85%nitro 5% p-oxide and 10% oil with no damage. Did not go faster so went to a safer mix. All I am saying is that the myth of Castor is greater than the reality with modern engines and I am still saying it does not hurt if it is what you want to believe. 3 years of flying 3-7 days a week and 100s of hours of bench running with no Castor is my experience. I repair engines every week and can attest to the varnish build up on the inside of these engines and what it takes to get it out and fit a new piston to the liner. It hones out easily enough but not everyone has a hone! Most of the build up is not when you are flying it is the residue sitting on hot surfaces after the engine quits, inside and out. Pull your head off sometime and look in the combustion chamber, black isn't it? This also hurts the combustion and sometimes is why you replace a glow plug trying to fix a problem, that is not the plug.
If you have several cases of fuel with high Castor content run through your engine( a modern engine) I will bet you your power is down and would come back with a light scrubbing on the liner walls and a new piston. As varnish is building the piston is having to wear to this new size. This too will cause excess heat which in turn will tend to make an unseasoned piston grow and now more heat. Some of the inconsistent runs are during this process. Once the piston normalizes this does calm down. Right before this years Nats I replaced a piston that had about 40 gallons run through the engine and lots more power was very evident from the first run. The engine was running fine before it just did not have the same poop as before with the same prop.
I, like Randy, also recommend a little Castor in the fuel as it does provide a little insurance for those mishaps with the needle but for me I refuse to clean it off my plane,epuipment,shoes,lines,etc..If I fly a Fox it will be to Larry's specifications, no questions asked.
Richard Oliver

Hey Rich,

WHAT engines are we talking about useing NO castor in. You'er RO-JETT of the FOX, OS, OR JUST FOUR STROKES?

Scott

Great Post

Scott, I am referring to any modern BB AAC type engine. ABC can survive some abuse bot not as well as AAC. All other types of engines and materials I absolutely agree with the use of Castor. When metal is wearing as fast as varnish is building it is good. Baffle top pistons all had hot spots that Castor was good at cooling and helping consistency. Rings are generally very porous and can use the fill from Castor. This is also a good place for Teflon additives. I do not however suggest them for AAC because of the tolerances and the need for a little wear to get good fits. After a long break in it is OK.
Richard Oliver

>Scott, I am referring to any modern BB AAC type engine. ABC
>can survive some abuse bot not as well as AAC. All other
>types of engines and materials I absolutely agree with the
>use of Castor. When metal is wearing as fast as varnish is
>building it is good. Baffle top pistons all had hot spots
>that Castor was good at cooling and helping consistency.
>Rings are generally very porous and can use the fill from
>Castor. This is also a good place for Teflon additives. I do
>not however suggest them for AAC because of the tolerances
>and the need for a little wear to get good fits. After a
>long break in it is OK.
>Richard Oliver

Richard.
I've used SLICK 50 in some of my old engines. I put in about a 1/4 oz to 8 oz of fuel. Did this about 10 runs and I had an increase of compression, not much about 5%.
BUT thank you for your post it’s a good one
Scott

>Scott, I am referring to any modern BB AAC type engine. ABC
>can survive some abuse bot not as well as AAC. All other
>types of engines and materials I absolutely agree with the
>use of Castor. When metal is wearing as fast as varnish is
>building it is good. Baffle top pistons all had hot spots
>that Castor was good at cooling and helping consistency.
>Rings are generally very porous and can use the fill from
>Castor. This is also a good place for Teflon additives. I do
>not however suggest them for AAC because of the tolerances
>and the need for a little wear to get good fits. After a
>long break in it is OK.
>Richard Oliver

Scott:
Aero 1 has no teflon additives in it, it's a combination of extream pressure lubes, antioxidants, anti-friction compounds, slickners, wetting and special heat sensitive polymer agents. I won't run my motors without it and several of the top competitors feel the same.
Larry

I do not wish to pick on Gary Weaver, but there are some misleading statements in his posting.

It is not clear at all to me that Combat engines, F2D or otherwise, operate under more load than does a Stunt engine. High rpm does not necessarily equate to high load; any engine which has shed the blades on a prop will really rev, but load from twisting the prop is gone.

I am not current on the F2D engines of today, but at one time, and when we were still using Fox 6s, my CL Combat team partner and I fiddled with reduced oil content in the fuel, the idea being to pack less weight around for a given amount of flight time. We quickly got down to (slightly) less than 15% total oil content with off-the-shelf oils, 7% with some trick oil (synthetic) with which I had had great success in 21s used in 1/8 scale RC cars.

Back to loads placed upon our CL Stunt engines, I think we all might be real surprised to learn how much load they must carry. Unfortunately, I have no data to drag out in making my case.

I do have anecdotal evidence, however: I was negotiating with a Russian outfit over bringing in rear-exhaust, piped 60s, the application being RC Pattern and back when the O.S. Hanno (Not-so) Special 60 was the kick-butt motor.

Dave Shadel bought a motor from an early shipment (testing purposes only, the deal eventually fell through) and while he liked the motor, made the comment that the rear bearing was a bit on the small side and would break.

I thought he was talking about losing the retainer, as that was the only serious rear bearing problem I had seen in years of flying both RC and CL, racing RC cars. But there was no point in making full-complement (all balls, no retainer) rear bearings, as the whole idea was to test as-produced units.

Following about 1 1/2 gallons worth of flight time on 45/10/10/35 fuel, the 60 turning an APC 12-12 prop, there was slight graunchiness (technical term, don't let it scare you away) when pulling the prop through.

Back home, I did indeed have a rear bearing problem: One of the balls was split in half! Okay, it was more like 1/3 of the ball had been chipped from the other 2/3; but upon first glance it appeared as if it had been cleanly whacked into two equal parts.

I had a couple dozen of these motors, proved to my satisfaction that all would lose rear bearings after no more than two gallons of relatively nasty fuel (by RC standards, although 45% and slightly higher nitro content was not particularly unusual in RC Pattern at the time), notified manufacturer of both the good news and the bad news.

How does this relate to our CL Stunt motors? Well, only remotely, I suppose. We don't tend to use fuel with nitro content much higher than 20% or so, many use a lot less, we don't slam high-pitched 12-12 props on them, and we don't pull vertical for a long time at maximum output.

Still, I suspect the piped 60s out there and the Saito four-strokes I am currently flying are dealing with two or three times the load one would assume from just watching the models fly the pattern.

I welcome comments from others, especially a proper definition of "load," how to discuss it in reasonable terms, any measurements of same that might be available, including simple measurements of head, case and exhaust temperature.

I'll chime in with a little bit here......

A now passed personal friend of mine who was an industrial chemist did some analysis on all the available synthetics of the time.

Of the cooler running synthetics, measured with a thermocouple on a number of my piped stunt engines, most contained amongst numerous other things, glycol. One of the by-products from the glycol in the combustion process is superheated steam, which carries heat out of the engine, so yes, synthetics can and do have coolong ability.

We proved that on some motors 5% castor substituted into s 22% synthetic fuel did run cooler. On some engines 10% substituded castor was required to note a temperature drop.

>I'll chime in with a little bit here......
>
>A now passed personal friend of mine who was an industrial
>chemist did some analysis on all the available synthetics of
>the time.
>
>Of the cooler running synthetics, measured with a
>thermocouple on a number of my piped stunt engines, most
>contained amongst numerous other things, glycol. One of the
>by-products from the glycol in the combustion process is
>superheated steam, which carries heat out of the engine, so
>yes, synthetics can and do have coolong ability.
>
>We proved that on some motors 5% castor substituted into s
>22% synthetic fuel did run cooler. On some engines 10%
>substituded castor was required to note a temperature drop.
>
>BRI

Super Heated Steam??
600 degrees at 450-PSI min. AAHHH Pistons would seize, Rods would bend.
I think you mean latent heat transfer of BTU’S. Superheated Steam would make a model engine a dangerous unit. HOWEVER, I know what you mean BRI.
Scott

Most synthetic oils we use ARE glycols. Which means that they're related to antifreeze, not castor or mineral oils. Why is this? It's because glycols are soluble in methanol, while mineral oils and most vegetable oils are not. Castor oil is the exception among vegetable oils because the fatty acids that make up the triglyceride molecule have an -OH group at the end, making it polar and thus capable of dissolving in methanol.

Glycols differ from triglycerides in that they vaporize and burn at lower temperatures, and don't form varnish at high temperatures. Bud Bodzioch, who worked for Castrol, and had access to all sorts of industrial lubricants, once gave me a can of the oil that he was using in his 1/2-A mixtures. It was a synthetic triglyceride that was alcohol-soluble. It had the advantages of castor (high burning point), but didn't varnish as easily. Problem was that, in time, it would form waxy flakes (which you could filter out).

Isky, When I was racing giant scale and mixed 100 to 1 oils in methanol fuels it would leave waxy flakes on the carb screen. I always wondered about that stuff!
Richard Oliver

Yes Richard every head I remove when running castor blends is black. However for two seasons I ran JBK fuel. 1/2 castor 1/2 synthetic 20%. When I would pull the head on these engines it was always super clean like new. I dont know why it worked out that way. But for dome reason his fuels didnt turn the head black on the inside. Any ideas?

Have you had a chance to run that 61 I gave you at the contest? How does it work?

Hi Doug, Yes I ran it and won the contest in Baton Rouge with it.
Richard Oliver

That was really good fuel. I ran it for three years. My OPS actually got cleaner as I ran. It was a used motor with a little build up but after one season it was like new. I dont know how he did it but his castor wouldnt leave residue on the engine. I also ran it in my PAs for two years and it was a good fuel. The Hazmat killed him and he quit shipping. To bad, it was a good blend.

I've heard that if you run synthetic-based (or maybe even synthetic-castor blend) fuel in an engine that has been varnished by castor use, it removes the varnish within a run or two. Which is why one should never run synthetic fuel in an old engine that has been run with castor all its life (you end up losing compression). Again, it's never happened to me personally, but if it works, it sounds like an easy way to regularly devarnish engines. Every month or so, run a couple tankfuls of "de-varnisher" through it. Might be just the thing to do with Cox 1/2-As, for instance (these are notorious for varnishing up and losing power).

I suspect ones' mileage, in this case, would depend a lot upon which particular synthetic oil is used in that particular fuel...

>Hi Doug, Yes I ran it and won the contest in Baton Rouge
>with it.
>Richard Oliver

Egads....

What are we doing wrong?

Could you please list your formula for the Ro Jett?

What sort of oil, and was it specifically meant for alcohol-based fuels? Speculation would be that it's wax, or gum, or oxidized oil..

In the case of Castor, I keep hearing stuff about flakes of wax that come out of the oil when subjected to cold temperatures, and people tell me that one has to get "degummed" Castor to prevent this from happening with your fuel, and the degumming process involves subjecting it to cold temperatures, and then filtering it. I have no way to verify whether this is true or false, and frankly, there is as much mumbo-jumbo and voodoo about oils floating around as there is about airfoils. Remember that Red Max thing about Castor oil producers changing from pressing the oil to chemical extraction, thus causing Castor to separate from the alcohol some years ago? Hard to know what to believe (though you can confirm what I said earlier about the chemical makeup of Castor by looking it up in an encyclopedia).

It was in the early days when I was switching from Gasoline to meth. I do not remember the oil as it was 10-12 years ago and I was trying anything I could get my hands on at the time. In pumper carbs(walbro and in this case Mikuni,spelling?) the fuel hits the screen first at the carb and at this point it is cold. The screen would clog in a flight or 2.
Richard Oliver

So this is the point after the fuel enters the air stream? That's interesting. Did the stuff feel waxy, or oily?

I don't claim to know anything about this stuff, but you've got me interested in it, too...

Isky, No it is internal to the carb. As the fuel inters the carb it is filtered then it goes into the bowl and then through the metering system. At the time we thought it was parifin.
Richard Oliver

>Isky, No it is internal to the carb. As the fuel inters the
>carb it is filtered then it goes into the bowl and then
>through the metering system. At the time we thought it was
>parifin.
>Richard Oliver

It could be carnuba wax (you know the good stuff for waxing your cars). This is present in raw castor oil, but is separated out in the pressing process. Good (AAA Bakers) will be fine. But some cheaper stuff, that did not go through all the pressing processes or was chemically extracted (The stuff Red Max got ahold of) will sometimes have these little flakes floating in the oil. It won't hurt the engine, but it will clog things up.

Which can lead to lean runs, which are bad.

I suppose one should always filter ones' fuel at some point before it hits the needle valve.

I wonder if the wax is what coats the (castor) beans.. plants usually have a waxy coating to keep the moisture in.

Len,

carnaúba waz is extractedm from the carnaúba palm tree, they grow a lot here in Btazil

Aldrich told a story about using bearings with less than C3 clearance, and ending up with balls that split. Probably not the same problem as this, but..