I was reading my owners manual and i saw that the Subaru recomendations are .
Non Turbo Models -Normal Oil SAE 20W50, API-SJ or superior.
Turbo Models - Synthetic Oil SAE 15W50 ,PPI-SJ or superior..
What does that mean??
For exemple,,what is the difference between 15W50 and 20W50??wich of those is better for my WRX wagon??
I live in Brazil very Hot all year..