On the old engine that got replaced.
I switch to AmsOil 20 w 50 on all three cavities at 2000 miles.
At 5000, the SM at the dealership decided to convince me to shift to Syn3 on all cavities. Warranty issues he explained.
Well, after a Primary Chain and a Head gasket leak, I had the crankshaft runout done at 7100 miles.
They are still scratching their head on how did I ride the engine into the dealership. It was way out and I got another engine. I believe the Amsoil saved the engine, but the engine would have gone anyway due to weights scissoring on the crankshaft.
I am for Amsoil.
Just my .02.