Why multi-viscosity synthetic?

[medic]

Why does a Group IV & V oil need to be a multi-viscosity? A SAE30 synthetic will continue to flow well below the freezing point of a dino 5w-30. Is this just to keep the public happy (same numbers they are used to) or is there an actual reason?

 

[Ken2]

"Multi-viscosity" is an odd term. All it really means is that the oil passes both a cold and a hot viscosity test. A straight vis oil has not been tested cold (well, it probably was tested cold by the blender, but we don't know if it meets SAE J300 specs).
http://www.tribology-abc.com/abc/viscosity.htm#SAE


Ken

[ September 30, 2003, 10:26 PM: Message edited by: Ken2 ]