Last week was differential oil day. This weekend was transmission flush day. If you have a full size lift or pit, this would be an easy job. On jack stands, it isn't hard, but it is more time consuming due to the limited movement you have, and a little scary, though it's mostly psychological. After getting the car up on jack stands, I pushed it hard from side to side and front to back to make sure it wasn't going to go anywhere, and it was rock solid.
Because I wanted to do multiple flushes to get as much of the old transmission fluid out, I was not looking forward to spending $250+ for transmission fluid for D4, which I knew was a great fluid. I run it in my Z4M, and know many people use it and have good experience with it, but I was really curious about Dexron VI, because after all, the AT in the ZHP is a GM transmission. As I researched, I learned that the GM Automatic Transmission - A5S390R - also known as the GM 5L50 Hydra-Matic was used in a variety of cars and SUVs including the Cadillac XLR, STS, and SRX, as well as some models of the E46 and BMW X5's. The 5L50 is basically a heavier duty version of the A5S360R (5L40E). What I learned was that many BMW X5 owners switched to Dexron VI without issue. I learned that Cadillac dealers use Dexron VI to service the Cadillacs with this same transmission. I then turned to forums, and found many satisfied E46 owners, but one troublesome report. However, after digging more, the one troublesome report turned out to have extenuating circumstances. The owner had also reset his transmission adaptations. So, BMW superseding my transmission oil number with Dexron VI, Cadillac using Dexron VI, and many positive reports, I felt it was close to a sure thing to use it, and that it would be superior to D4 in chemistry.
I found genuine Dexron VI for $3.79 per quart from Rock Auto, and promptly bought 21 quarts. Yeah, that's a lot, but I had plans for it. I did several drain and fill cycles this weekend, and I'll now drive for several hundred miles, and do a final drain and fill.
There are other how-to's, but this is an overview of the process I used.
Here are the parts and tools I used. Even though the pan bolts are only tightened to 7 ft lbs, which is basically "snug," I broke out the small 1/4 torque wrench set to 84 in lbs. I'm using a T45 torx bit with a 10mm ratcheting box end wrench for the tight squeeze of the fill plug.
Here is the "green" label on the GM transmission. Punch in the part number on a BMW parts search, and you'll get Dexron VI as the new part number:
http://www.realoem.com/bmw/enUS/partxref?q=83220024359
https://www.getbmwparts.com/oem-part...id-83220397114
Yeah, the pan was nasty. I didn't take a pic, but I cleaned up the outside before re-installing it.
Here is my ultra-short Torx 45 setup. It's just a 10mm box end ratcheting wrench over a 45 Torx bit.
The procedure I did was:
- Cold fluid drain
- Fluid Fill until overflow
- Crank engine and slowly run through PRND S1 S2
- Fluid fill until overflow
- Turn off engine
- Drain
- Drop pan
- Pull filter
- Clean Pan, clean magnet, remove and clean gasket area
- Replace filter
- Replace pan with new gasket installed
- Fill until overflow
- Crank engine and run through gears quickly
- Turn off engine
- Drain
- Fill until overflow
- Crank engine and run through gears slowly
- Fill until overflow while engine is running and AT temp is around 100-125 degrees F checking with INPA
- Seal it up. Done until a few hundred miles.
Here is the pan dropped with the filter.
A couple of helpful hints:
- Remove all bolts except the four corners. Replace the drain plug. Loosen the four corners so there is about a 1/4" of exposed thread. Now break the seal on the transmission pan. This will allow you to pull down on the pan to break the seal without fear of a big slosh. Once the seal is broken, you can remove the final bolts and ease down the pan without spilling any.
- When you pull out the filter, it will likely have one orange ring and one yellow/white ring. There should be two orange rings. Look for the second ring inside the transmission. It needs to come out.
Here I have pushed up the particles on the magnet to show how much was there. There was a little in the bottom of the pan, as well. I believe this was the first time the fluid had been changed based on what I found. The drain plug was painted like the pan, the particles on the magnet, plus the black fluid, all lead me to believe it had never been done. So, first AT fluid change at 158450.
I first cleaned the outside of the pan with Tarminator and a general degreaser. Next, I cleaned the inside of the pan with lint-free towels, then for good measure rinsed it all with denatured alcohol and allowed it to completely evaporate. Then I realized I hadn't removed the old gasket. So, I got to do it all again.
I used a level on the transmission bolts and leveled the transmission for the final fill. For the first two cycles, I had the transmission angled slightly back toward the drain plug. This shot is actually from the first fill after the cold drain. The pan is still nasty in this photo.
The transmission didn't have any issues with reverse, slow shifting, etc, and after the fluid change, it continues to operate like it did before except that shifts seem to happen a little faster. I drove it about 30 miles after the change, today, and so far, so good. I'll report back from time to time on how the transmission is doing.
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