This is interesting.  I was unaware that the limit only applied to the
lighter viscosities.

This was the source of my confusion.

-Wes

Mike S wrote:
>
> The limits placed on phosphorus and sulphur content by the API SM spec
> only apply to weights 0W-20, 5W-20, 0W-30, 5W-30, and 10W-30. None of
> those weights are suitable for a VW. There is no limit on zinc, except
> indirectly as a part of ZDDP, which is due to the phosphorus limit.
>
> This is found on page 61 of this API document:
> http://www.api.org/certifications/engineoil/pubs/upload/1509_16thedition042007.pdf
>
>