The implications that Amsoil does no testing or somehow Amsoil CVT fluid on the market for years now damages CVTs truly needs some proof from the folks making the claims at this point.
I'm not saying Amsoil causes damage. I have no data, you have no data, we have no ability to collect any data.
Amsoil bothers to say on their website they put their fluid in 4 Taxis in las vegas? Um, that's great, but still nothing approaching a proper analysis of how their fluid works for 25 cvt specs they claim it meets. It makes me far less confident TBH, just advertising chaff.
Subaru went to the trouble of making their own CVT's. So they should have many many times the data on their specific unique transmissions than Amsoil has? And Subaru has the most interest in getting it right, and even they even offer the longest transmission warranties in the business.
So in the absence of any other data, I'm going with the guys getting paid to minimize warranty claims for Subaru, and minimize production costs. If they thought one fluid was good enough for all their transmissions, wouldn't they just say that? Save some headaches?
A CVT isn't complex but the pulley/chain interface is the one thing that's pretty sensitive to the fluid and any slippage or odd wear isn't really fixable? Maybe subaru fine tunes the metallurgy in each trans type? I have no idea, no data, and I doubt amsoil does either, but for near equal dollars, I'm just getting the subaru stuff, and would recommend others do the same, based on the logic I outlined, but if you have a better argument, I'm all ears.
I'm not sure we have the equivalent of the Magnuson-Moss act here either, which makes me lean towards the OEM fluid.
For engine oil, I'm with you, use whatever meets the specs, but engine oils don't have carefully selected friction modifiers.