BMW Repair: 528i transmission, pan gasket, dexron 3

Question
I have a 1997 528i with aa5s 310z tansmission, and according to BMW spec, this should be on a M3! I bought the car just 10 months ago and is running fine. Should I use DENTRON 3 oil if I want to change the transmission oil?

Answer
Leon, If your transmission is indeed the A5S310Z then the operating fluid manual says to use Dexron 3 or 4. The M3 with this trans uses ESSO LT 71141 fluid. I believe that this fluid is yellowish. Uncrew the drain plug just enough to get a couple of drips on a white piece of paper. If the sample is red like Dexron then you have your answer. I would remove then transmission pan and replace the filter and pan gasket for good measure. The trans is a side fill so you have to pump it in from the side since there is no dipstick tube to fill from. Fill trans till fluid emerges from the fill hole. Start the engine and continue to fill untill fluid emerges from the fill hole again and have some on put the car in drive and reverse and back to park again. The trans has to be filled between 30-50degrees  celsius. (86-124F) to get correct level so you have to fill fast. Remember if you shut the engine off with the fill plug open the fluid from the torque converter will come rushing back into the pan.
-Evan