I used Amsoil 2000 for 3 seasons, on 3W100 Started to loose RPM, tore engine down it was carboned up with one stuck ring.
Was it run lean at any time? was it run rich? It may have been. I would say too rich if any.
But it did carbon up.
I have switched to 100-1 mixing it at 80to1. Motor is running strong. But Im going to look inside at the end of every season. Everybody says this works and that works, but your not going to know till you use it, and take a look.