My brother left me '89 quadrunner 250 4x4. Try to find out what kind of oil I should put in engine and rear differential. There is two drain plugs, but only one oil cap and one level window. The Engine and the differential is a one block. The oil cap is located on the right rear side of differential and there is mark on oil cap says sae-10W40 I'll be thankful if somebody tells me what kind of oil I should put in engine and differential, and what about filter and where it is located?

 

Valvoline makes an ATV oil. It has the additives for wet clutches. People use all kinds of engine oil and say they have no problems. The oil filter is located on the right side. It is a round cover with 3 bolts. It is easier to change if you remove the rear tire.