Yamaha BRUIN 350 Manuel Du Propriétaire page 122

Engine oil
Make sure the engine oil is at the specified level.
Add oil as necessary. (See pages 8-21–8-31.)
CAUTION:
_
G
In order to prevent clutch slippage (since
the engine oil also lubricates the clutch),
do not mix any chemical additives. Do not
use oils with a diesel specification of
"CD" or oils of a higher quality than spec-
ified. In addition, do not use oils labeled
"ENERGY CONSERVING II" or higher.
G
Make sure that no foreign material enters
the crankcase.
_
Recommended engine oil type and quantity:
See page 10-2.
5-13
EBU10842