[_GW_]

I'll do coolant first. I haven't received any pushback on that.

I'll tackle the transmission fluid change after that by seeking a dealership that has more experience doing it.

[_GW_]

And then I find this gem of a document. See excerpt below.

https://www.google.com/url?sa=t&rct=...eKnZc2XvOEr_a1

"Older automatic transmission models, which do not have “lifetime fill” should have ATF and filter services every 15,000 miles if using petroleum ATF; every 30,000 miles with synthetic.

However, the modern automatic transmissions are different.
No one knows exactly what BMW’s proprietary ATF is, so no one knows if there are viable alternatives. We do know that BMW dealerships charge about $500 for an ATF and filter service, due to the price of the ATF. And that’s assuming you can get them to do the job, which is not often the case.

Bavarian Autosport (www.bavauto.com) is now importing the proprietary “lifetime fill” ATF at reasonable prices, which they sell along with filter kits, for independent BMW shops and do-it-yourselfers.

It is risky to drain a previously un-maintained automatic transmission with high mileage, even though if it were my car I would probably chance it. Still, I have seen it happen too many times, where a well-meaning owner or technician performs an ATF and filter service on a neglected but well-shifting automatic, and then all of the sudden it starts slipping. I can’t explain it, but my feeling is the fresh ATF flushes a bit of sludge from a place where it was doing no harm to a place where it does do harm. Overfilling, underfilling, and cleanliness are also issues in ATF and filter servicing, but these should not be problematic for a professional BMW technician, dealer or independent.

BMW has backed off their lifetime fill mantra for automatic transmissions, currently recommending an ATF and filter change every 100,000 miles.

My inclination is to tell people to change “lifetime” ATF and filter every 30,000 miles. However the fact is, I've seen BMW automatic transmissions that were maintained break anyway. In that event, say it happens at 90,000 miles, you would like to have that $1,500 you spent on ATF and filter changes to put toward your new automatic transmission. And if I told you to spend it on maintenance you’re probably not going to be very happy with me. On the other hand, I have seen maintained automatics last 200,000 miles. I have also seen unmaintained automatics last 200,000 miles, although both are very rare. There's just no predicting with these transmissions. When you choose to buy an automatic transmission, you also buy into the vagaries of the darn things, which is one reason technicians hate them.

Whether to maintain a modern BMW automatic is up to you. I am washing my hands of automatic transmissions – I don’t like them, I don’t buy them, and I don’t mess around with them under the car. At the end of the day, for long-term durability, order the car with a manual gearbox"
© 2007 Mike Miller

So there you have it. Maintaining these automatic transmissions could be like "Dammed if you do, Damned if you don't".

[n3985]

Take any dated information (2007) with a grain of salt.

Everyone recalls the adage of 3,000 mile oil changes which some folks still swear by for any and all cars. But engines and oils have advanced so should maintenance intervals.

Who would know best? The manufacturers such as ZF so heed their recommendations over "...my uncles lifetime mechanic buddy that once worked for NASA and swears drinking ATF keeps him healthy."

[ezaircon4jc]

The problem with "lifetime" is the definition of "lifetime." I discovered the hard way that lifetime means the lifetime of the product. That could be 15 years or 15 minutes, depending on how long the product lasts. Whenever the product fails, well, that is it's lifetime!