How does an oil qualify for 0w status?

Patman

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Is it just being lower than a certain cold cranking spec that allows an oil to qualify for 0w status or are there other factors? What does a 0w oil have to achieve in terms of it's cold cranking specs? And is it at -30 or -35c with the new SL formula changes?
 
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quote:
Originally posted by Jay: For the 0w designation the motor oil must have a hot kinematic viscosity of 3.8 cSt @ 100*C or greater to start with. Then it must have a cold temperature pumping viscosity of less than 60,000 cP at -40*C and a cold cranking viscosity of less than 6,200 cP @ -35*C with no yield stress.
The 3.8 cSt @ 100°C would be for a straight 0w oil. For a 0w30, the vis at 100°C would need to be between 9.3 and 12.49 cSt.
 

Jay

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Are you sure, G-Man? For example, a 20w-20 designation is possible but not a 25w-20 because of the minimum kinematic viscosity requirement of 25w. [ May 01, 2003, 12:10 AM: Message edited by: Jay ]
 
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quote:
Originally posted by Jay: Are you sure, G-Man? For example, a 20w-20 designation is possible but not a 25w-20 because of the minimum kinematic viscosity requirement of 25w.
Yes, I'm sure. A 0w30 would need to have the cold cranking and puming vis of a 0w oil, and the high temp vis of a 30 weight.
 
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