Ducati MONSTER 821 2016 Owner's Manual page 240

VISCOSITY
SAE 15W-50
The other viscosity degrees indicated in the table can
be used if the local average temperature is within the
limits specified for that oil viscosity.
238
10W
20W
20
30
20W–40 20W–50
15W–40 15W–50
10W–40
10W–30
–10 0 10
40
20 30 40 C
Fig 166