Nothing wrong with approvals … but I’m having trouble finding ZF8 approved ATF made by Castrol, Mobil, Pennzoil, or Valvoline ? Why is that ?
There's no margin in it. We're talking about a very low volume product. When most non-Bitogers see "lifetime fluid" from their OEM, they take it at face value.
By the time a lube company has invested in R&D to come up with a fluid that will pass licensing ZF requirements, then it goes through the licensing process itself. Who knows how many roadblocks, intentional or not, exist there? They produce a batch, package it, warehouse it, ship it, market it, all for what? Where is the money to be made? There's no rationale in producing and marketing a product meant to replace what is perceived by the great majority of the public to be a lifetime fluid.
If Shell is making the majority of the OEM ZF fluid, why are they not selling it under one of their own brands? Either they have deals with ZF, Audi, BMW, FCA, et al to not compete with them, or there's just no margin there.
As far as Valvoline saying "also recommended for," they have little liability exposure. If a ZF or two is
proven to be damaged by Max Life, they'll just pay for the repairs. The responsibility for this proof lies on the damaged party. Just cheaper to pay for repairs. If there were a rash of failures, which the OP has stated he believe hasn't happened, you'd see that recommendation disappear quickly.