Quote Originally Posted by kikoteng View Post
If I used, for example, a less viscous oil, say 10w-40, how do i know if it's the right viscosity for my engine ? Would it shake more, make weird noises if I used the improper viscosity ?
Per experience, the only main concern with using a "thinner" oil would be when your engine is already aged or high mileage as this would have more propensity to leak through worn seals/gaskets. Other then that, there's not much concern with using 10W-40 or even 0W-40. 0W-30 or 5W-30 can still be used also but isnt adviseable on the high mileage or "heavy use" vehicles.