The warranty is a contract. You do not follow the obligations agreed to under the contract, you forfiet any benefit of said contract.
The manufacturer is obligated only if you follow the warranty, and you get problems anyway.
All those class action suits against the auto makers proved that.
I'm not interested in what Amsoil says about it. I don't care if it's been in the oil business for 38 years.
Ford has been in business for 107 years. Never once filed bankruptcy. Didn't go for gov't bailouts. Never, as far as I've been able to find, has had any problems stemming from using mfg approved oils in any engine they've designed.
No company that makes oil is ever going to convince me that they know better than the engine makers.
Especially if they are too cheap to have said engine makers test their oil.
How about this. Link to cases where, oh, let's say, Ford, paid. Even though the car owner violated the warranty.
No Amsoil links.