Just thought I'd flog a dead horse a bit on the old transmission fluid debate.

My '95 540i just turned 145K, with 40K miles since the last transmission fluid change. I replaced the OE Shell fluid with Pennzoil Multi-Vehicle ATF at about 87K miles, and then changed it again at about 104K.

Draining the fluid this time, I decided to do a pre-emptive valve body rebuild because of the mileage on the car.

The fluid that came out looked just slightly burned -- what went in looking like cherry cough syrup came out with a slightly orange hue. It was clear and smelled OK -- well, about as good as it smelled when it was fresh.

The magnet in the pan had just a dusting of iron on it, far from the furry look it had when I opened it up 53K miles ago. Overall, it all looked quite clean and very satisfactory.

The torque converter has wanted to unlock in fairly low-torque situations as long as I've had the car. It's had me adjusting the throttle while driving to accommodate the whims of the transmission. Fortunately, Bimmernut archives link to ample how-tos on doing the rebuild. They're very helpful, and I'm grateful to those who took the time to post them.

The valve body internals were quite clean -- a couple points with small accumulations of iron mud here and there, but overall not needing any significant cleanout. I had a couple cans of brake cleaner handy to blast out the goo, but I didn't find anything worth going after with a chemical flush. Neither check ball showed any appreciable wear, but the big channel gasket was kind of brittle.

I've driven about 100 miles since the rebuild, and the torque converter seems to want to drop out of lockup a lot less. Of course there's an adaptive feature to the transmission control, so we'll see if there's any further change on tap in the coming miles.

I think maybe a 40K interval is a little long for the Pennzoil product -- 30K miles might be more appropriate. But the transmission seems to be holding up very well on it.