Fuel Dinosaur

2-stroke fuels with high castor work fine in 2-stroke engines, but NOT well in 4-stroke engines. I recommend 0-4% maximum castor in 4-stroke fuels for Saito and other 4-stroke engines. Too much castor seems to gum up 4-strokes pretty bad. A few purists prefer NO castor in their 4-stroke engines. I prefer about 2% castor to lubricate the bottom bearings and keep rust down a bit better than a 4-stroke fuel with no castor. You might look up an old article on Google, basic homemade model fuel as the search terms to give you an idea what and how much oil, nitro and methanol are in various fuels for engines in common use. I would not use 2-stroke fuels containing a lot of castor in any of my 4-stroke engines. My Saito formulation is 3.6% racing castor, 14.4% Klotz Techniplate oil (all by volumes) and the rest percentages clean, dry methanol. Works great in the .91 and even in the Saito radial 170. Hope this information is of help.