What kind of engine oil do i use for my Yamaha tri moto 125cc 1983

 

Any motor oil you find on sale. I had a 1987 Yamaha 250 moto4 I just put 10w-30 in it and its still running to this day.

 

Don't forget the 1983 YT125 is an oil injected 2-stroke so you're going to want to fill the oil injector reservoir with a decent 2-cycle oil (we usually go synthetic here as it uses so little oil over time, the increase in cost is well justified). You also have a transmission oil fill for the bottom end and for that just about any 4-stroke formalization designed for motorcycles (these usually have additives for a wet clutch to prevent slipping - as is the case with your YT's automatic clutch) should do.