Copperhead
Veteran Member
A multi viscosity oil like, lets say 10w30, would be at the equivalent of a 10 weight oil at 0c and a 30 weight at 100c... give or take.
Since a 10 weight oil would flow better than a 30 weight would the use of an oil heater actually thicken the oil up?
Well, let's test that one. Take a 10w30 and put it in a freezer. Take another quart of 10w30 and heat it at around 200F in your oven and see which pours easier or if the warmer one is thicker. Might surprise you.
Sure, a 10w30 will flow better at 0F than a straight 30, but you will be hard pressed to find a 10w30 that flows thicker at room temp than a 10w30 at 0F. In a multi-grade oil, the oil is NOT the thickness of the first number and then thickens to the weight of the second number. The first number before the "w" is the winter flow rating, not the weight of the oil. A 10w30 or a straight 30 are both 30 weights. It is just that with more refining, and viscosity improvers, the multi-grade flows better at a lower temp. Hence, it will flow in winter like a 10w, but it is in fact a 30w.
It is a common fallacy that the first number in a multigrade oil is the weight of the oil at cold temps and the second number is the weight of the oil at operating temps. The first number only represents the way it will flow in cold temps, not the weight. Check with the Society of Automotive Engineers (SAE), and they will confirm this.