Mixing Castrol r30 castor with synthetic oils

[RLorange]

Hello everybody sorry I have not had time to contribute anything to this forum for a while...

Question: I was keen to try a Castor/Synthetic oil blend in my well worn in 70cc engine to extend its life so I purchased the first Castor based oil I could find which is Castrol r30.

At 50% mixed with my regular synthetic Motul 800 oil the r30 seemed to lean up the engine dramatically raising the idle speed, also the fuel consumption reduced dramatically! interestingly instead of causing the engine to overheat is actually kept the engine much cooler than before. Plus there was a major boost in power.

I ran it for a little while like this before I discovered that the jet and pin in my carby was gummed up hence the lean running.

After a cleaned carby and at 20% the castor seems fine and the engine still seems to have a better ring seal than before BUT. Massive quick build up of a strange brown carbon deposit on the piston top. This won't clean off with acetone!! I have chipped it all off and had a look at the rings which seem clean but it certainly is a pain to remove this all the time.

After some net research I have seen many mentions not to mix Castrol r30 with other oils... Though not much mention why. Then I read many recomendations here on this forum that mixes are fine.

Is it just my type of Castor that shouldnt be mixed?

Is the funky build up a result of mixing oils or would it be the same (or worse) with straight Castor?

Would a pre-blended Castor be safer and is this little experiment just not worth the risk?

 

[Bikeguy Joe]

I'll just comment that castor, while the most awesome of all oils, does build up a bullet proof layer of carbon like "stuff" in no time. It seems to make the piston seal better and add a resilient coating sorta like a natural teflon.

 

[RLorange]

Yeah the whole engine feels tighter yet smoother since I started running some in the mix. My theory was that because of the sloppy build tolerances these engines could really benefit with some of that magic Castor Varnish. The head dome has a dark brown smooth coating from the Castor which is as smooth as teflon! I have left it there to boost compression and the stuff on the piston head is pretty easy to chip off. I'm thinking it may well be worth the hassle with all the benefits.

Should I be scared of mixing oils though? some bad reaction between them? The Castrol Mineral I have at the moment has mixed ok in a test bottle and has not changed consistency or reacted in days now.

 

[Saddletramp1200]

There is a legend as told by old 2 stroke riders, if you mix 1/2 oz of caster oil and 1/2 oz Marvel Mystery oil ALONG with your 2 stroke oil that the lube properties improve and build up is reduced with a better throttle respose and more top end. I don't know if it's true

 

[sprocket]

I wonder whether it might increase power to have some strong build up on top of the piston, since compression ratio for these engines is about 6:1 only. Would be great to figure out how to get it up to a decent 9:1, without having to for example weld extra material on top of the cylinder (people have done that since there's not much material to remove from the head to increase compression). Probably leaving the build up on the piston crown will help compression ????
By the way, I'm new in the forum, Hello to all of you guys !

 

[Mr.2Tcycles]

Hello all!
My first post on the forum, I have built a mountain bike with a chinese engine (67cc) in it so far about 3/4 gallon of gas used. On my first tank used Walmart Super tech 2 stroke at 20:1 but the plug quickly became caked in carbon although the bike ran and did not foul. Second tank switched to Maxima Castor 927 at 20:1. Noticed a smoother engine almost immediately. Plug comes out a nice dark tan. Maxima 927 is a 20% mix of castor and the rest synthetic esters and additives. I love the smell. Read somewhere Castor mixed with even a small amount of "Dino" oil will cause problems, but article never said what problems anybody know the issue with the mixing here? People have been mixing their own oil for years in the RC field.

 

[Pablo]

Just a couple thoughts. Most issues with castor oil and mixing are from fuel containing ethanol.....yes I know castor does OK with straight methanol and nitromethane, but somehow with gas/ethanol/castrol/additivized 2 stroke oil mixes, the oily faction gets weird. It causes stringers and weird junk in the combustion chamber.

The thing is, Castrol R20 is not straight castor.....it has some very interesting additives, that make it a bit better with gas and alcohol, but it may not mix well with other oils.

Frankly I would get some straight castor oil from SIG or one of the other suppliers and carry on with your testing.....

 

[RLorange]

Very interesting thoughts people. On the comment about build up boosting compression: I have gained compression by getting rid of the bottom gasket and using a high temp silicone gasket goo instead. The piston is a close as is comfortable to the head gasket and I have not had any problems so far after hundreds of kilometers and steep hills

 

[Mr.2Tcycles]

How about milling a few 1000s of an inch of the top of the jug where it meets the head. I guess you gotta be careful about not taking off too much, it may interfere with plug or the head gasket.

 

[RLorange]

Yeah that would work just as well, actually it is superior but I don't have the tools to do that. I did spend and hour with a piece of glass and some wet 'n' dry glass paper but barely shaved anything off and was starting to curve the surface. The spark plug is fine but you have to leave more clearance than first thought because there is up and down play in the piston. You can't have the piston smacking into the head even lightly. Noticable boost in power though. Had mine done so long ago I kind of forgot until I rode another bike recently. No change in performance acceleration-wise or anything so it is mainly noticable up hills or into head winds then it just trucks

 

[Mr.2Tcycles]

I have actually seen it done with a brand new LARGE flat whetstone some water, and a lot of patience, with the jug of the engine of course. I'll try it when this engine starts to wear out.

 

[sprocket]

By removing the bottom gasket you mean the gasket between the cylinder and the crank case ? That sounds like it will boost compression a little bit, but at the same time it will change the timing of the engine, I mean at how many degrees the transfer ports open, and when the exhaust port opens, etc, just slightly though. I've no idea it that is good or bad but it'll be changing it. Removing material or a gasket from top of the cylinder shouldn't affect the engine timing. I think the timing in these engines is not optimized at all, I'll look into that in the near future, I'll keep you posted.

 

[Technocyclist]

how about that Castor oil from the pharmacy? is it the same Castor oil?

 

[Mr.2Tcycles]

No castor oil from the pharmacy shouldn't be used, it contains sugar, and other additives that are not good for the engine. Don't do it. Use Maxima 927 (personal favorite) or Benol or Castrol A747 (spendy!!) or Techniplate from Klotz. These are specifically blended for 2 strokes. Cutting corners can get expensive later on.

 

[Pablo]

how about that Castor oil from the pharmacy? is it the same Castor oil?

It's not degummed. IOW's it's not truly in oil form. Buy the pure oil from Sig.