Whats the best oil for my 1990 toyota celica all-trac?

my car is a 2.2 cylinder, it has 198,300 miles, and its a gt. i dont know if gt means turbo engine, but thats what the guy at the shop, that it was turbo. in the manual it says 10w-30 or 10w-40 of api grade sg, recomended sae...?