Originally Posted by tclederman
The W refers to a grade at a "cold" or W Winter temperature. No "W" means a "hot" viscosity grade.

I do not know if I have ever seen a 10-30; but, I suppose that is possible. I have seen 10W-30 (as described above).
Tim, I left the "W" off because I was too lazy to type it. I had no intention of confusing the discussion. The whole intent of my initial post was to make sure the original poster understood that all of the oil does not stay in the filter because there were no anti drain back provisions then. I certainly had no intention of starting a debate on who knows most about the viscosity of oil and the construction of bypass oil filters. This has gotten way past where I tried to contribute, to the point of picking nits, so I'm done.


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