Well, Catrol"M" is not just any "caster oil", but refined, degummed, high grade quality by one of the largest oil companies in this world. Are there any other users of Redmax that can back up their claims? How good is their model synth oil? I would love to see it compared to the excellent German Titan oil ( by Fuchs) IMHO, For model engine use, it is no use to put emphasys on the "plating quality" in gas/meth/nitro full scale racing or drag engines. In the sixties, I have read reports on Spanish off road engines that ran for an hour or so on pure gas without damage, just by the sparce remainder of oily particles in engine and tank. That was the only way for the reporter to get out of the desert somewhere between California and Mexico. That goes to show what a well run in engine will accept (for a while at least). Having spare parts at hand, I also have run my screaming .21 MVVS combat engine on as low as 8-10% castor oil for 3/4 season, surprisingly without any mechanical damage, save for a sticky balky engine after a while. Yet, after cleaning out the gum from the piston assy, I reverted to 20% synth Titan.
) because it gives me a stable all year round, though slightly lower, performance.