My engine is a 4JJ1, in an Isuzu D-Max 4wd.
Factory oil is Besco Duramax 10w-30.
Other recommendations in the handbook are all 15w-40: Shell Rimula R3X, or R2 Extra or R2; Exxon Delvac MX; Caltex Delo 400 or Gold. And a few others listed.
I ran the factory 10w-30 oil for for about the first 2...