I just opened my box for my Fuji .099 the other day. I bought it NIB from Hobby Shack in the 70's. Because of this thread I took a look at it again. It has a supplement in there, that has not been mentioned here. The supplement states to "read the instruction manual, do NOT run any fuel that is not castor oil based. Do not use synthetic oil fuels in this engine."

FWIW...