Yamaha YFM350S Owner's Manual page 371

MODEL YFM350
Engine oil:
-20˚ -10˚ 0˚ 20˚ 30˚ 40˚ 50˚C
10˚
Type
5W/30
10W/30
10W/40
15W/40
20W/40
20W/50
Recommended engine oil classification: API Service SE, SF, SG type or higher
CAUTION:
In order to prevent clutch slippage (since the en-
gine 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 specified. In addition, do not use oils labeled
"ENERGY CONSERVING II" or higher.
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