I just bought a 1996 Yamaha Timberwolf 4 by 4 four wheeler. It didn’t have a manual but I’m trying to figured out why it smokes when I go through water and what kind of oil I should put in it?

 

Is it not just the water turning to steam when it hits the hot exhaust and engine cases?

If you are getting blue smoke from inside the exhaust, check the engine breathers are connected to the airbox, and if the are not, change oil right away, as you probably got water in the crankcase, which lifted the oil level to where it got burnt, but was replaced with water.

Any 10/40 engine oil is OK if it is suitable for motorcycles (oil immersed clutches).

 

Will it mess up my four wheeler when’s it hitting the hot engine? Thank

 

No, Quads are made to go through fairly deep water. Yamaha's electrics are not the best protected against water getting in, but should be OK in normal use.