Hi,
i'm driving WAJA

i have some questions in choosing the right "oil" for my car
last time i was using castrol gtx, but then ppl recomment me the roadster because of the cheaper price (means price of 1 roadster < 2 castrol)

is that true that SM is better than SL??

CASTROL GTX SM/CF (5000km)
15W~40

ROADSTER API SL/CF (10000km)
SAE 15W~50

i'm noob about car thingy anyone can tell me? thx~