I'm rebuilding the engine so I'll be replacing all of my gaskets and seals. I went ahead and bought some Valvoline Max life full synthetic because it was on sale for 3.95 a quart and I couldn't pass it up. If it's a bad idea then I'll take it back and get conventional oil, I just figure if I'm gonna put all the effort onto regaining my tired old 64hp it might help it along to use synthetic oil and a premium filter. Also replacing vacum lines and rebuilding the carb. If I have time and money I may re route the exhaust to be a little straighter and gut the catalytic converter to allow for better flow... I'm not trying to build a street racer just a DD that I can put a few more miles on and be trail capable.