SuperTech Full Synthetic oil - Anyone doing 10k OCI with it, and any issues with sludge/varnish.

[Bill7]

I had the valve covers 15000 miles prior when I put the engine in and it was clean.
It was the lower end supertech synthetic. Not the 20K mile variant if I remember right.

The car had seen a bit of towing, a few highway trips, a winter commute ... Definitely qualified for severe service .

I know it's scientifically impossible to know for sure, but in your opinion, would any Group III synthetic have had the same result as SuperTech of the 11k severe service with towing and the new little varnish under the valve cover near the PCV that you saw?