ATF change, ATF lab report, ESSO no longer recommended by BMW or GM

[TaMbALoLoNg]

?? got the breakdown of the elements and everything huh, Thats just way to deep for me to worry about.

[realchef]

Originally Posted by dkl

John,
Thank you for the excellent info. This assured me that I did the right thing when I'd changed mine out at 50K miles when everyone else on the planet told me to leave it alone. I even had dealers that looked at me funny and refused to do the change.

I'm with you. '01 at 47k and going to change this summer.

Thinking about diff fliuds too. What do you guys think. JCL, I think you said before not to change the Transfer case, just diff?

Tambalong, I agree. After you turn it on one of two things happens:
1. Car go.
2 Car no go.

[JCL]

Originally Posted by John Galt

I understand that, but given that GM made the transmission internals, and they use that same package in their cars, it does give what they say a lot of weight. I don't think that a reprogrammed shift pattern is going to take the fluid from lasting 100k miles to lasting forever. Whatever you think about that, the high TAN alone from my fluid says it was time to change, despite what BMW says about the fluid not needing to be changed.

Here is a link to my full report: D67388.pdf - Windows Live

Thanks for the full report. A baseline number would be really helpful as well, if anyone out there has a low-mileage Blackstone lab report on the factory fill fluid.

In the 'good old days' (prior to electronic shifting controls) we dealt with automatic transmission fluid overheating by installing 'shift kits' from B&M and other performance parts outlets. They were essentially revised check valves and springs for the transmission valve body, which reprogrammed the shift points for higher revs, and firmer shifts. They were good for trailer towing as well as performance V8 applications in muscle cars. They reduced fluid temperature, and the likelihood of clutch damage. It is not the shift point (in rpm) that matters as much as the shift characteristic, since clutch plates wear when the shift is happening, and not between shifts. That is so true, that for some applications engineers commonly measure transmission life by the number of shifts, not the number of hours or miles. So, IMO, changing shift characteristics has a significant effect on fluid life.

I fully agree that it doesn't make the fluid last forever. Just like the famous story of the pack of gazelles in Africa that is pursued by the lion, however, you don't have to be the fastest gazelle. You just can't be the slowest. Applying that to transmission life, my point is that it doesn't have to last forever. It just has to exceed the useful life of the rest of the vehicle, whatever that may be deemed to be.

The Dexron specs (which have been improved since your vehicle was produced) list various oxidation and stability tests. The TAN indicator varies by transmission manufacturer, but some published numbers I have seen are that TAN cannot increase by 3.0 or 3.25 over initial baseline numbers, whatever that baseline number is. I don't know what the initial TAN number is for your fluid, but there are other oils out there on the market in the 1.5 range. By that calculation, your fluid was about halfway to the change limit. All of this is an estimate, but I wouldn't say that your fluid was dangerously high. It was trending towards a replacement point, absolutely.

Interesting topic, thanks for the post.

[JCL]

Originally Posted by realchef

Thinking about diff fluids too. What do you guys think? JCL, I think you said before not to change the Transfer case, just diff?

I think that the differentials and transfer case do not have the same issues around the risk of changing as the transmission. They are straightforward drain and fill applications. If you are going to change the differential fluid, you may as well change the transfer case fluid at the same time. I think of them as 100,000 km or 60,000 mile change points, but that is just my opinion.

I would ensure that you use factory OEM fluid in all of them, as BMW does not publish good (universal) specs for aftermarket fluids and there is nothing wrong with the factory fluids, and little to be gained by playing roulette with aftermarket blends. That also covers the risk of not using the correct fluid for the clutches in the x-drive transfer case.

[John Galt]

Originally Posted by realchef

I'm with you. '01 at 47k and going to change this summer.

Thinking about diff fliuds too.

I did the transfer case and diff about a year ago:

http://www.xoutpost.com/x5-e53-forum/...-diff-oil.html

http://www.xoutpost.com/x5-e53-forum/...que-specs.html

[chefwong]

FWIW, I'm at least 15K miles with 2 drain bolt changes on the transmission, with the 3rd being a full pan drop/filter change.

Transfer case & diffys were done around 15K miles ago as well.

1st drain bolt was using OEM Esso.
2nd and Pan Drop was using Amsoil ATF.

Amsoil ATF in the TC and Severe Gear 75W-90 in the diffs for me.

The only fluid I had to mess around with was the PS, and I settled in on M1 for this app. The viscosity of the other 2 were slightly lighter and definitely did change steering feel characteristics.

[X5 Meister]

Anyone replacing their drain bolts with ones that have magnets in them?

[John Galt]

Originally Posted by X5 Meister

Anyone replacing their drain bolts with ones that have magnets in them?

I don't think it makes much of a difference, but I did one for the oil pan:

http://www.xoutpost.com/x5-e53-forum/...oil-diffs.html

The ATF pan already has a magnet in it.

[X5 Meister]

You sure that Honda one will fit? There isn't some BMW reseller that sells them anymore?

[chefwong]

John -
Curious do you do trending UOA's on your oil ?
I'd love to compare ....