Quote:
Originally Posted by dawudih
why is mobil 1 0w-40 not labeled energy conserving on the api starburst? all the other weights of mobil 1 are. the engine starts up alot quieter & less harsh sounding in the morning with this oil.
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The engine also starts up a lot quieter mostly because the oil is a lower viscosity when the oil is cold. This gives more cold protection since the oil is thinner at startup, but as the it warms up it also gives the thicker 40 viscosity protection.
-Mike