Dexron III and a lot of it

[KHE]

It doesn't follow that a spec for GM engines would drive people to the dealer, unless that oil is available only for oil changes at the dealership, which would cause consumer revolt: lost sales. In places I get oil changes in out-of-warranty cars, I notify the shop of which oil I want and how much (if they have to ask) and give them a couple of days to get it in before I bring in the car.

There is a federal law (Magnuson-Moss warranty act?) that states if a manufacturer requires the use of a product in order to maintain the warranty, they must provide it free of charge to the consumer.

[joeb]

Our local fleet/farm has 1100 different fluids for sale. Literally dozens of hydraulic fluids, and auto fluids as well. They sell univ auto trans fluid for $2/gal. I suppose a casual observer might say this stuff barely meets the specs of so and so? So, WHAT brand of car is this stuff made for? I assume it's GM? Ford stuff is different. Chrysler is different. It's certainly not Honda/Toyota fluid. So, someone actually makes this stuff. And everyone here says its stupid to use it?

[JohnnyG]

And everyone here says its stupid to use it?

I don't recall anyone saying that at all. If you're asking about Dexron, you basically have two choices for a GM car: Dexron III or Dexron VI. Dexron VI is the better choice for longer trans life. If you're asking about motor oils, things get a bit more complicated. The currently offered motor oils that meet the DEXOS certification, are tested (we assume) by GM and meet or exceed all of the requirements of GM's validation process of typically 300,000 miles. Nobody said that you will damage anything by using non-DEXOS oil, but somewhere down the road you might end up with stuck rings, or a poisoned CAT, or valve rap on cold startup.....little things like that. None of which will kill your car, just not allow it operate as well as it should.

Z15 began by pointing out that some non DEXOS oils might be better than other others in certain ways. But the main discussion here was to clarify that DEXOS certification ensures that the motor oil is "good enough" (for lack of a better term) in ALL regards in order to meet the engineers design requirements for however long the item was DESIGNED to last. Maybe we all failed to get that point across.