Yamaha BIG BEAR YFM400FPP Owner's Manual page 120

Engine oil/Transfer gear oil
Make sure the engine oil/transfer gear oil is at the
specified level. Add oil as necessary. (See pages
8-13 ~ 8-25.)
Recommended oil:
-20˚ -10˚ 0˚
5W/30
Recommended engine oil classification:
API Service SE, SF, SG type or higher
5-13
20˚ 30˚ 40˚
10˚
10W/30
10W/40
15W/40
20W/40
20W/50
EBU00492*
50˚C