Hi All:

     Recently I have been thinking about keeping my engines "clean" by adding a synthetic oil to my fuel as suggested by others.   Clean is translated into avoiding a castor buildup on the piston, sleeve, wrist pin, ball bearings etc.

     In the past, I have used ATF to store my engines and as an after run oil with no problems.  For example, I took my ST G21/.35 out of storage, mounted it on a plane, fuel it up and it started and ran well after only ONE flip of the prop.  This engine had been in storage for over 30 years! What could be better? I checked the engines once a year and added a drop or two of ATF, wrapped them up again and placed them in storage.

     As an after run oil, it appears to keep the engines "clean."

    Years ago, I used only FAI fuel and did not have a castor build up.  I then switched to a fuel that contained only Klotz 100 as a lube and I could not see any problems.  This was a mix of 25% Klotz and 75% alcohol.

    Oh yes, I have found that ATF mixed 50% with acetone makes a great penetrating oil!

    Perhaps we are overthinking the "Castor Build up" in our engines. 

    Thoughts or suggestions concerning the idea of keeping the engine clean?

                                                                                                                             Stay well,

                                                                                                                             Frank

   

The ATF that is widely available in the UK will not mix with acetone. Anyone have any theories as to why?

Andrew.

After running when the engine is still warm I mix 25% ATF with 75% naptha and run three good primes through the engine. This flushes the castor out and coats everything inside the engine with ATF.

MM

True, poor choice of words on my part.

Better to say that acetone is fully miscable with water ( able to break down the meniscus in all proportions) whereas a mineral oil base fluid is not.

It is my understanding that acetone and ATF is partly  miscable and will benefit from mechanical agitation before use.

Thanks.

Hmm, the few times that I have used an acetone/ATF brew was fully contained within a glass jar.

Engine place inside if it, shaken - not stirred like Bond's martini, stuck parts tested frequently and then left to sit for a couple of days.

It was very cheap to concoct, easy to use, did not have a chance to evaporate and imminently reusable.
Oh, and it worked a treat!

Perhaps the key here is to acknowledge that NO solution can penetrate unless there are micro fine fissures or fracture lines available for it to do so and giving the parts a wiggle every now and then helps to create them.