Castor oil in 4 stroke engines

[Former Member]

[This posting has been removed]

[GrahamWh]

But not for their engines - they use fully synthetic!

[Jon H]

Switching away from castor in an engine that has always used it should not present any problems. I have done it a bunch of times and it was always fine.

The comments about oil and cooling are valid but its the methanol itself that has a far greater cooling effect than the oil. Spill methanol on your hand and you get frost bite almost straight away. Methanol evaporating in a crankcase or cylinder head does the same which is why high nitro engines run cooler as they run a richer mix. This cooler temperature can be bad for reliability but that is another story.

The oil % story is another issue as well and while i am sure that most modern engines will be happy on 10% synth or less i dont recommend it for general use as i dont want to hear about it if it goes wrong. Also 5% top quality oil will work much better than 15% chip fat and when it comes to home brewing, a great many go for the cheapest gear they can.

[ASH.]

Old timers swear by Castor - it has a higher flash point than synthetic and so protects the engine in case of accidental lean runs.

As to oil content,, I'm now using 12% Klotz (2%castor) reduced from 18%, 6.6% nitro. To my surprise I find a significant increase in power which I can only put down to reduced drag from oil friction something I had previously been highly sceptical of.. However, I have found the Saito 72 runs hotter especially when flown at WOT. The engine is tuned to optimum on both needles and so there is very little oil residue to clean up from fuselage underside.

How does Klotz Technipate compare with ML70 apart from huge price difference..? I have heard European oils are more superior to the American stuff which is ester based PAG or POE..!??

I am concerned about the carbon build up on exhaust valve/ chamber. I will have to find some way to clean it off when I come to do the bearings. Anyone know the best way to do this without completely dismantling the valves,rockers etc. I was thinking of getting an UltraSonic cleaner.

I know I know, I probably need therapy but I'm hooked on the aroma of burning castor.

 

Edited By ASH. on 17/03/2019 20:27:37

[GrahamWh]

I've tried an ultra sonic jewellery cleaner on a sooty exhaust - didn't really do much.

[J D 8]

ASH, You found as I did in my grasstrack racer 40 years ago that using synthetic oil gave more power. I thought at the time that at the start of a race [ grasstrack races were short] cars on castrol R were slower off the line because the oil was still a bit stiff so to speak.

[Jon H]

Posted by ASH. on 17/03/2019 20:17:12:

Old timers swear by Castor - it has a higher flash point than synthetic and so protects the engine in case of accidental lean runs.or.

Edited By ASH. on 17/03/2019 20:27:37

No, it wont. This is a myth

The whole 'lean run' protection claim is flawed as the engine will not run in a lean condition. Lean mixture is a mixture beyond optimum performance and results in an rpm drop and then rapid overheating, followed by a flameout. A lean engine will rarely run more than a few seconds before it stops.

The root cause of this misunderstanding is that a perfectly tuned engine may overheat and stop due to poor cowling design or the use of high power for a long time. This overheating is misdiagnosed as lean due to the high engine temperature and deadstick.

So if we ignore the lean part and focus on the overheating part, castor is very good at holding on at high temperature. It was better than synthetics available in the past and so it gained this reputation. Unfortunately, as was previously discussed earlier in the thread, while the castor might have prevented your engine seizing in the old days it also took payment for that service by laying a coat of varnish on the piston. This varnish is sticky and created friction causing more load, more heat, and more chance of this engine overheating again. It would also bake onto the fins, which got dust and debris on them, resulting in a nice insulating blanket over the engine. None of this is good for the engine.

Since then synthetic oil has come a very long way and its tolerance to heat is such that castor really offers no advantages. If you run your engine so hot that a decent synthetic oil burns off then you deserve whatever you get

Klotz regular techniplate is fully synthetic if memory serves, its the super techniplate that adds the castor. The regular flavour is fine for use in pretty much everything at 15% and would most likely be fine as low as 8 or 10%. If you want to play safe then 12-15% will be fine im sure.

[Former Member]

[This posting has been removed]

[Peter Christy]

Jon is right, regular Klotz Techniplate contains no castor - its the super Techniplate that has a trace of castor (about 2% IIRC).

My son and I were involved in testing when Bekra heli fuel was being developed. Originally the oil content was 15%, and it was fine. It only got increased to 18% because OS said anything less would void their warranty. The only difference it made was a very slight power drop and a much oilier model!

Tom: Castrol used to supply castor oil in two types "R" for petrol engines and "M" for methanol. The "R" does not dissolve well in methanol, and vice versa! I don't think they've used it in motor oils since the first world war, when it was used for rotary engines!

Back in the late 60s and early 70s I used to race karts - the serious kind, with 200cc engines and 4-speed gearboxes! In our group we had four karts, each with three members sharing a kart. All the other teams were running on Castor based fuels (these were Villiers 2-strokes). Our team leader insisted we run on molybdenum disulphide based oil. We were the only team to regularly complete a season on the same piston! The castor teams used to get through two or maybe three.......

--

Pete

[Jon H]

Posted by Peter Christy on 18/03/2019 07:56:09:

Originally the oil content was 15%, and it was fine. It only got increased to 18% because OS said anything less would void their warranty. The only difference it made was a very slight power drop and a much oilier model!

yup. My 8th scale nitro car runs a 21 2 stroke at up to somewhere near 40,000rpm. It uses 16% nitro 12% synthetic oil fuel without issue. Given the general torture of being a car engine in terms of heat and revs is far beyond anything a fixed wing engine will see. If 12% is good enough for that the its good enough for the rest of us!

As for OS, my 15fp was designed for 20% castor but it runs much better on 15% synthetic. Model technics did testing some years ago and found the critical point was actually somewhere down around 2 or 3% oil so im pretty sure we use way too much oil in glow fuel. But that might be worth another whole thread!

[Former Member]

[This posting has been removed]

[Chris Walby]

Run a 2 stroke lean for a moment on methanol , no problem after this one we moved to 4 strokes and never looked back.

Only needed new piston. rod, liner, small end, big end and main bearings and shaking the loose bits out of the exhaust! Pulling the bits of ring imbedded in the head and the crankcases out, we didn't bother.

[Jon H]

Posted by Jason Channing on 18/03/2019 21:18:34:

Hi Jon . I can assure you that My Engines can run past optimum mixture and they do not not cut out , but they will run very hot, sizzling hot.luckily these are only My old engines when playing around with them and showing My son how not to tune engines.

They wont. if the RPM hasnt dropped off then you arent past optimum. If the rpm has dropped and its still running then its clearly in a bad way as the rpm has dropped off. The point i was getting at is you cant run an engine lean and still get maximum performance. A lean engine will always stop in pretty short order.

Chris, many engines simply cant dissipate the heat they generate fast enough. They dont have to be 'lean' to cause the sort of damage you see there. Heli and car engines are the most vulnerable to that sort of thing.

[extra slim]

Good chat, one parameter not mentioned is Oil "thickness/viscosity".. There appears to be a consensus on Oil percentages, but from experience of testing a little for a manufacturer the viscosity, I think measured in centistokes proved an interesting exercise. My two strokes loved the "thin" fuel, heli and fixed wing applications, whereas my four strokes ran hot and weak on the thin stuff (bar my YS engines), and my saito and OS four strokes much preferred the medium viscosity.. so I guess viscosity is an important factor together with oil %age..

[J D 8]

This piston came from my trialing competition Land Rover, The result of to much heat and rev's. Much like the one above. Fueling would have been fine as it is from a diesel.

[Jon H]

Posted by extra slim on 19/03/2019 10:52:44:

Good chat, one parameter not mentioned is Oil "thickness/viscosity".. There appears to be a consensus on Oil percentages, but from experience of testing a little for a manufacturer the viscosity, I think measured in centistokes proved an interesting exercise. My two strokes loved the "thin" fuel, heli and fixed wing applications, whereas my four strokes ran hot and weak on the thin stuff (bar my YS engines), and my saito and OS four strokes much preferred the medium viscosity.. so I guess viscosity is an important factor together with oil %age..

Quite true, not all oils are created equal. I tend to recommend avoiding the thin ones in our engines but to be honest the viscosity is only half the story as it comes down to the film strength.

Whatever the oil is in the aspen2 petrol is really good. very thin but it sticks to everything and seems to polish to a shine. I keep meaning to ask them what it is and see if it will mix with methanol. If so there is no reason not to use it at the same ratio as i do in the petrol engine. 2% oil glow engines, anyone fancy that?

[Martin Harris - Moderator]

I thought that perceived wisdom was that petrol has a lubricity that methanol doesn't have. Would the percentage not need to be slightly greater for glow or is it another old wives' tale?

[michael kuss]

Hi Jon , without starting a oil war does the klotz kl-200 pass the test in the Laser engines ? I have one of the 100 singles and a 200 & 360 twin if that makes any difference .Other than cool power the klotz is about the easiest for me to get . Cheers

[ASH.]

Reading all the posts above I think I'm being converted to fully synthetic (I am so easily swayed ). But no, I cannot give up totally on castor just yet! It not only helps me to sleep better but castor vapour soothes the olfactory nerve with nostalgia..

Does anyone know or have any info on ML70? I'm thinking of switching from Klotz.

Also, what's the best way to remove carbon without dismantling and grinding?

As to the varnish mentioned above, I've seen photos of brown stain coating on engine cylinder &piston which had only been run on fully synthetic.

No info on oil on Aspen website - *LINK*

[Don Fry]

ASH, what might work, is heat the engine to high temperatures, say 400, 500 ° C, and flood it with oxygen, or chlorine. That would burn it off. Apart from that, nothing much touches carbon

Edited By Don Fry on 20/03/2019 19:39:42

[ASH.]

What about cooking it in antifreeze in a crockpot? It's a age old recipe which people say works. I just don't want to discolour or affect the aluminium and other metals. Any ideas -anyone?

The chlorine is interesting.. I will have to experiment.

 

Edited By ASH. on 20/03/2019 20:29:43

[Former Member]

[This posting has been removed]

[Jon H]

Posted by Martin Harris on 19/03/2019 16:43:46:

I thought that perceived wisdom was that petrol has a lubricity that methanol doesn't have. Would the percentage not need to be slightly greater for glow or is it another old wives' tale?

In the case of a 2 stroke there is some truth, but in the case of a 4 stroke its nonsense as there is never any fuel in th crankcase, only oil.

Michael, KL200 is fine. 15% of that will be plenty

ASH, carbon removal is pretty much a mechanical process im afraid

[Martin Harris - Moderator]

Posted by ASH. on 20/03/2019 18:31:19:

Does anyone know or have any info on ML70? I'm thinking of switching from Klotz.

I believe it's the oil used by Southern Modelcraft which I've used since 2002 with excellent results. The 10% nitro mix that I use in virtually all my engines does contain 2% castor (and 15% ML70) and I haven't suffered from any noticeable carbon build up or varnishing.

Edited By Martin Harris on 20/03/2019 21:50:59

[J D 8]

ASH, Leave the chlorine alone, it strips old castor alright, also does a pretty good job of etching the casing as well. Guess how I know this.