The OEM manual says the Transmission...

[JCL]

Originally Posted by TiAgX5

The point I was making still stands regardless of if the BMW trans was an existing or clean sheet design. The ATF sold thru the dealer network is nothing more then an existing spec fluid, provided by a contracted fluid manufacturer, identified by the BMW designated part number. BMW will NEVER put the spec details on the bottle because this would only provide the purchaser the info required to purchase fluid elsewhere at a lower price. Keeping the customer buying from a BMW parts source = $s!

I agree completely that the fluid that BMW relabels isn't made by them, it is a third party fluid that is certified though. It isn't a multi-vehicle universal fluid, which is the topic under discussion.

Ghost has used a fluid that isn't a Dexron fluid; even though Mobil make and sell a different fluid that is Dexron certified, if he wanted to specifically use Mobil. The risk is using a fluid that is blended to try and meet a wide variety of specs. It is sort of like using a pair of water pump pliers on a precision machine to loosen a bolt. It may work. But it is far more likely to cause a problem. And since we have seen a high incidence of problems anyway (which is the reason that posters want to change their own fluid) I think it is worth actually using the correct fluid.

You have in fact done the same thing based on the info you provided on the fluid you used. It is not an LT71141 fluid according to the Castrol site. It is a universal fluid, designed to reduce inventory charges for the shops that sell it. OK, that is a bit cynical, sorry.

Looking at the Castrol site for the particular fluid you used, they say:

Exceeds all passenger car and light truck manufacturer’s warranty requirements for vehicles,
transmissions, or power steering service where a DEXRON®-IIIH, MERCON®, or MERCON® V type
ATF is specified

They don't list any other specifications in that section. And that is the section that touches on things like their liability, which Ghost mentioned above. If you care about the liability, it is ONLY a Mercon fluid, although it appears to was also a Dexron III fluid when that spec was current.

Then they say:

Recommended for use in vehicles that require

• Honda, Acura — ATF–Z1 (except in CVTs)
• Toyota, Lexus — Type T, T–III, T–IV
• Nissan, Infiniti — Matic–D, Matic–J
• BMW — LA2634, LT71141
• Mitsubishi — Diamond SP–II, SP–III
• Hyundai — SP–II, SP–III
• Volvo

See the difference? Look further, at the product data sheet. There, they note that the fluid is certified to the Mercon specification. Looks from the wording that they were also certified to Dexron III, because they note the specification, and then say that they don't meet Dexron VI. GM doesn't license Dexron III anymore, so they can't legally say they are certified, which is just a commercial issue. I would trust them to be a decent Dexron III fluid in any case.

I know they cross reference the LT spec. But at the heart of it, it is still a Dexron III/Mercon fluid. Ask a transmission shop if you can use Dexron III in your ZF, and see what they say. Phil and others who rebuild transmissions will point out how risky that is. But the guy selling the oil says don't worry, be happy, it's all good. It's your call. I wouldn't touch it, myself. Just because you didn't have a problem doesn't mean that it is a good idea to recommend this fluid for this use. Statistically, you will be better off with the right fluid, but not 100% will fail. If you got lucky, then great, congratulations.

Just because your transmission has not failed, you can not conclude that your choice of fluid was right on the mark. If it was the other way around, and you had an immediate failure, you may be able to conclude that the choice of fluid was wrong. But just because it is still running is not proof. Proof will be when you can show that the transmission ran longer on this fluid than on the recommended fluid. You don't have that comparison set up, so the best you can hope for is that it is no worse than the OE fluid. And the worst is that it fails. It is a stacked bet, and that is why many of us say to use the correct fluid, not just one that a vendor claims is OK to use even though deductive logic (ie it is actually a Mercon/Dexron fluid, so how can it be an LT71141 fluid at the same time) proves that is illogical.