Originally Posted by kool168
the 5 represent flow rate and 30 represent thickness. so 0W40 should be for my car.
No, it represents the viscosity of the oil when cold (0) and warm (40). The oil you want to run would be ideal for an engine that operates in a very cold climate (the oil will flow pretty good when the engine is cold, minimizing wear), but runs very hot (the oil will remain pretty think, so parts get the proper coating of oil). In your car in this climate, a 0w40 will be very thin on start up, thus not protecting your engine very well, but then will be too think when it reaches operating temperatures, possibly hampering how well it flows. Exotic oil viscosities will not make your car run better – they are exotic for a reason.
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