Motor oil is used to lubricate the internal parts, the close tolerance and extreme heat necessary for combustion require a thin film of lubrication to keep all the parts moving smoothly.
Motor oil is lubricant used for internal combustion engines. Motor oil serves several important functions in an engine. It carries heat away from the engine as it lubricates moving parts and helps to prevent corrosion.
General Motors specifies 5W-20 engine oil for the 4.3 engines.
i believe they have an oil injection system on these engines
That's okay.
If you mean motor oil, yes.
Oil is oil period. You need to know "What viscoisity(weight) oil to use in the motorcycle?" These engines rev high and the right weight oil is extremely important.
15 is thicker oil and for bigger engines.
5W-20 ( certified for gasoline engines ) according to the Owner Guide
No. You need a specialized engine for that. These engines can burn other oils too, like burnt motor oil, vegetable oil, etc.
They run at a higher temperature so the oil breaks down faster.
Lubrication and cooling.
The motor oil to use in a 1982 Yamaha 250 XT 4-stroke dirt bike is a 10-30 or 10-40 weight oil. Castrol GTX Motor Oil that is of this weight is the best oil to use in off road bikes, because it is a cleaner oil. It will not gum up the works of smaller engines like regular motor oil.