ORIGINAL: earlwb
ORIGINAL: NM2K
I'm not ready to buy into the castor oil being bad for four-stroke model engines just yet. I've only been using castor oil in four-strokes for twenty some years. A lean engine run can cause damage regardless of the oil type.
Ed Cregger
I don't see any problems with using a little castor oil in the fuel. Castor oil does wonders for protecting the ferrous metal parts from corrosion where synthetic oil does nothing. So usually I can run a 4 stroke engine for ages before I have to replace bearings. But I see other guys all the time replacing bearings every year and they use 100% synthetic oil.
I recently put my Saito FA91S straight in @ WOT (thank goodness the ground was moist/soft) It seemed to come through unscated until I was doing test runs when I set up the C&H EI. About 20 minutes running @ high RPM revealed a leak developing in the front bearing. Looks like the bearing didn't survive the hit & is failing.
Anyway, the engine was previously stored indoors for 14 years after I ran the previous airframe through some picked corn stubble when I "range checked the radio in the air"! DOH!
It will be interesting to see how the "innards" look. The engine had moderate hours on it before it was stored & has had close to a gallon of fuel through it before the latest crash. Exclusive use of 15% Cool Power so we will see of the horror stories about lack of corrosion resistance for all synthetic oils are true.