Subaru 2001 Impreza Owner's Manual page 259

SAE viscosity number and applicable
temperature
B Recommended grade and viscosity under severe driving
conditions
If the vehicle is used in desert areas, in areas with very high tempera-
tures, or used for heavy-duty applications such as towing a trailer, use
of oil with the following grade and viscosities is recommended.
API classification: SJ or SH
SAE viscosity No.: 30, 40, 10W-50, 20W-40, 20W-50
Maintenance and service
OM-H2756
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