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Old 01-05-2008, 06:06 PM   #5
corn
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Join Date: Dec 2003
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Re: What the W means on the oil!!!

Polymers are added to a light base oil(5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

Forgot, W stands for winter...

Last edited by corn; 01-05-2008 at 06:09 PM.
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