DEx 6 is kind of a unique situation. Its a very specific formula developed by GM. For a product to be sold as Dex 6, it has to be Dex 6. Like Honda Power Steering Fluid, or X drive fluid. GM licenses the formula. I bet the best 'quality' is AC Delco.... I used Castrol when I did my tranny. got a case on amazon for pretty reasonable.

Your probably right. AC Delco is the genuine article.... Mr Good wrench and all that.

Use the brand that u r comfortable with. Castrol, M 1,
??Pep Boys??WalMart???, A C Delco Interesting discussion.

I think its tough enough to wrap your head around the fact that most of the e36-e83 BMW's run a GM transmission. SAme as on a cadillac. interestingly, I think the e36 transmission pan is slightly different, I had to source a gasket on short notice and the GM dealer parts department was open on a saturday. The equivalent GM application didnt have the same secondary pan (or the filter kit didnt come with it) that the e36 had.

My Transmission was dying a 191K. I have have the X since 14K miles. I changed it once at 104K as the transmission was starting to lag a bit. At that time I used Kendal Multi-trans as it was the only one that even mentioned the 8072b spec. I also changed it at 160K or so with Mobil 1. The transmission started dying slowly at 191K. I replaced it with a 45K used unit and put it Dex IV (Wal-Mart). Runs perfect Gas mileage way up. Proprietary formula, the Wal mart Super Tech stuff is fine. Now if I had the 4.4i with the ZF trans it would be a different story. But the 3.0i GM unit is nothing but a GM trans that uses GM fluid.

The Mobil 1 Dexron VI fluid is real Dexron VI. The Mobil 1 synthetic is a Mercon fluid, not Dexron VI at all. It is similar to the old Dexron III fluids, but can't be certified to that spec as the spec was retired.

If you check the tech specs the fluids are different with respect to viscosity. etc.

Use any certified Dexron VI fluid. Use a generic fluid at your own risk.

Although, Dexron VI is backwards compatible with all other Dexron fluid prior. This would included Dex 3 or Mercon. So.... what is your point?

Simply that the generic fluid sold as Mobil 1 synthetic is not actually a Dexron fluid, whether III or VI.

The Mobil 1 Dexron VI product would be fine to use.

Alternatively, if you want to use a Mercon fluid go ahead and use Mobil 1 synthetic. It is a different product.

Dexron VI can't be reverse compatible with Mercon, as the two specs are mutually exclusive. But people seem to want to buy something that says synthetic on the bottle, even when it is a lesser fluid, so Mobil 1 produces a product for those consumers.

I see people mentioning that the temperature needs to be monitored when filling the trans back up, anyone follow this in the procedures? How would this be done by a backyard mechanic?

Put your car up on jack stands so the rear wheels are free to spin. After filling with Tran fluid. Run/idle engine and gently shift Trans through the gears. Park, reverse, drive. Let engine idle with the Trans in dive and rear wheels spinning fo 10 to 15 minutes. Then shut car off . Place in park. Check fluid level.
The hot fluid will expand and the excess will flow out. When it stops running out. Replace the fill plug and it's right. If you suspect a leak check in 30 to 60 days.

**FYI. My Trans at 175 000miles. Seems to use about half a qt in 90 to 120 days (10000 miles) with no external leaks that I can find. I don't know where it goes but it just keeps running like new. So I just keep checking it.

What about the front wheels?

Do a drain the day before and let the truck sit over night. Even though you may have drain the fluid out of the trans a larger quantity of fluid is still in the Torque converter and trans cooler.

The next day. Start adding ATF to the trans with the engine off until it comes out of the fill hole. Replace the plug, but do not tighten. Start the engine up and go through all the gears pausing at each gear for about 30 seconds. With the engine still running and the truck in park or neutral crawl underneath the truck, remove the fill plug and continue adding ATF until it starts coming out the fill hole again. Replace the fill plug and tighten to the appropriate torque. You are now done. If you follow this procedure you should be well below the limit of the trans temp that is not to be exceeded while filling the trans. Remember ATF expand with heat and the hotter the ATF is in the trans the less ATF you will be able to get back into the trans.