Originally Posted By: Basil
Last thing... AMSOIL has updated their top 0W-30 from SSO to AZO and brought up other viscosities to have the same robust add pack. One thing I didn't like about SSO: they said it can go 15k/25k, but around 7-8k (even after cleanings) startup noise increased dramatically. I'm surprised such a robust/expensive oil would degrade to that point so early in it's expected life. I've been adding 4 oz Auto-Rx as a dose and I don't get that noise till maybe 12k and it starts up much much easier and quieter throughout that 12k life.
Anyway, I'm planning to try out their new ASL to see if that helps. I'm in SoCal, but noticed that even though the SSO is thinner than the 5W-30 GTX, the cars start up SO SMOOTH and QUIET in 100F weather more so than cold so I'm assuming the 0W being too thin is a bunch of [censored], so it's hard to say what the ASL will do. Worth a shot.
I think post "clean up" (obviously, the engine needed it or else you wouldn't be doing it) any oil would struggle to stay clean and not be good for up to its maximum drain interval.