In Reply to: What does ##W-## mean for motor oils?? (eom) posted by KGY on January 09, 2000 at 04:17:38:
The "W" does not mean "weight" or "winter".
If the number is followed by a "W", it relates to the oil viscosity tested at 0degrees F.
If not followed by a "W", it related to oil viscosity tested at 212degrees F.
If rating has both number designations, it is called multi-viscosity. Ex: 20w-50