drin21, if you manual suggests 75w90 you should use the RP max gear. it'll meet the requirements of your transmission. you can use either 5w30 or 10w30. i wouldn't expect any major milage increase if you switch to 5w30 though. yes, castrol, mobil and most other oils are group III. RP, redline, some motuls are group IV. some motuls are group V.

olidotcom, anytime ready yung pwesto mo

baby_scar, we have 5w40 but stocks are not always available. it's also more expensive at 690/quart. 7 quarts for engine. 4 quarts for atf kung drain/refill.