Exactly the the argument and points/idea. Thanks.
Did you read that 2014 up Mazda's never need a transmission fluid change? Its not even mentioned in the manual.
Whats funny is all the cars i have done transmission fluid changes had failed transmissions at some point (1-Ford, 1-Dodge, 2-Buicks, 1-Acura) changing fluid every 20k. My Acura blew the transmission at 95k, with the new transmission i decided not to change the fluid and it went another 200k no problems.
Ill never change the transmission fluid again.
I know of cars that say that they never need a transmission fluid change. To me that's ridiculous, fluids degrade over time and metal parts break in when new so you will have those little shavings being circulated around, guess not so much an issue in a transmission than an engine but a trans will heat up and an overheating fluid isn't good. What if I use my car for transport, hauling 4 adults with luggage everyday, in the city, in hot summers, up hills, and maybe taking the car for spirited drives up twisty roads to the top of a mountain every weekend? Is that abnormal use? Not really. Maybe, if I only drive myself a few days a week and live right off a 55 MPH highway with no stoplights to and from destinations. But telling me that my transmission fluid never needs changing? Does the trans still have an oil pan, a filter, a drain plug and fill plug? If it never needs changing then why are those there? I know manufacturers are making "sealed" transmissions but all that means is that the dip stick is removed and that they want you to take it to the dealer to pay a lube tech $120 to check it, when with a piece of wire or a decent OB2 reader, an app and a wrench I can check my fluid for $20 or less. Sucks that I even need all that, but its better than having to pay someone to plug in a fancy trans temp reader, waste my time at a shop, and trust them to say my fluid is either low or good. For instance in my Toyota, they said the ATF never need changing too, but then once issues started to be noticed with fluid, they revised that to 90k and now 60k.
The transmission manufacturer usually has more accurate service intervals than the auto manufacturer. Unless you were doing something wrong or those cars were driven very hard I've never heard of transmissions failing after servicing fluid every 20k. Were they just drain and fills or flushes? Were pans dropped and filters and gaskets changed? Was an equal or better fluid put back in? Was warmed trans temp fluid level correct after service? When you say every 20k, do mean you flushed trans after getting the car already used or was it every 20k miles new from the dealership? Unusual for people to service a cars transmission while still under warranty, and if it is, then the dealer does it. Usually a dealer only does a check fluid level and top off. The only time a trans fluid is serviced is if that manufacturer interval says it needs says its done near the end of the warranty, 60-90k, maybe earlier at 30-45k. You don't specify what conditions happened in those cars that failed.