ORIGINAL: PipeMajor


When you say you've had no problems at all does that mean you haven't fried an engine yet or is this based on a teardown and complete inspection of your engines?

I know a lot of C/L types who build/rebuild engines for a living. Most of them say whenever they get an engine which has been run on synthetic oil they always see scoring on the crank pin, excessive wear on the rod journals, peeling liners and other related issues. Virtually all synthetic oils have a lower flash point than castor oils. They will combust at temperatures a model engine can achieve. Modelers like the synthetics because they are easier to clean off your airplane. Sure, castor will cause varnish but offers the best lean run protection and rust protection of any oil. There were a whole slew of world calibre C/L stunt guys who experimented with synthetic lubricant based fuels back on the 80's. Every single one of them lost an engine. It's not unusual for these guys to get 2,000-3,000 seven minute patterns on a good engine. When they started using (and I quote) the "kool-aid" fuels their finely blueprinted and tuned engines, they were quickly ruined.

As I said, I use a fuel with 18% oil on my ABN ball bearing TT 46 Pro but I'm careful NOT to overlean it. Even at full throttle I can hear the cackle of it just hitting a four cycle stance. If I wanted to go all out I'd move up to a 20% oil. Sig Champion exclusively for my C/L engines.

For plain bearing modern engines (such as the OS FP and LA series) then a 22% blend of half synthetic and half castor get run through those.

For the plain bearing iron piston old metallurgy engines they get a MINIMUM of 25-28% oil which can be a 50/50 mix of synthetic and castor. You'll never get a Fox 35 to break between a 4 cycle and 2 cycle setting in the air unless you run it on 28% all castor fuel.

Would you run a modern 5W-20 oil in your 1960's Mopar muscle car or '32 Deuce? Doubt it...