ORIGINAL: jaka
Hi!
Your'e right! Running in is not rocket science! If you just avoid some of the pit falls like dirt and running lean our engines will just run and run and....
But the modern synthetic oils we have in Europe are better than castor oil in that they don't leave a lot of residue (black stuff) on the piston wall and combustion chamber.
Try them and you will never go back to "Old castor oil" for ordinary sport engines (Racing engines are a different matter). I do miss the smell due...there is no synthetic oil that smells as good as castor oil.
Regards!
Jan K
Sweden
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If your castor lube is leaving black stuff on your cylinder/piston walls, you have inferior castor oil not suited for model use, or you are overheating the engine severely.
When using the proper type of castor oil, you will see NO varnish build up during break-in if the mixture is set properly. The only time that castor leaves varnish is during a lean run, or after a lot of running at normal mixture settings - and I mean a lot. This is why castor is superior to most synthetic oils available for our use.
I am not familiar with your synthetic oil, so I have no opinion regarding its superiority/inferiority and cannot comment in this regard. However, I have used castor oil for nearly fifty years and I can say without a doubt that anyone seeing a severe varnish build-up (light tan) or, worse yet, carbon (black) with little running, is either not using the same type of castor oil that I use to this day, or they are experiencing severe engine overheating. The latter can be caused by running the engine extremely lean, or not lean, but with insufficient cooling air/too much prop load. This opinion is based upon my experience with the castor oil that is sold for model use in the USA only.
I am beginning to suspect, after reading comments from Europeans about castor oil, that their castor is not the same as ours in the USA.