[Dick Schneiders]

There is a known problem with the auto tranny whining in these cars, after a filter change, if they did not use an OEM filter or if they reused the little O-ring and it was worn. I purchased, last month, a 1999 740i and one of the first items I had done to it was to have the auto tranny fluid and filter changed. I did a lot of research on various internet forums and found many references to this whining when aftermarket filters are used, or if the O-ring was reused.

The filter needs to have the word "filtran" on it, if it is a true OEM filter.

While I am new to the 7-series, I am not a new BMW owner and have done a lot of research on them. Even though these later model trannys have what BMW calls "lifetime fluid" (a terrible description, in my opinion), the fluid should be changed. A typical time frame is in the 75,000 mile or so range, to be conservative. What happens is that the fluid generally won't cause any problems until the car is out of warranty after 100,000 miles, and then when the tranny fails you have to pay for all the repairs out of your pocket. This is what BMW means when they say the fluid is "lifetime" - it will usually last for the *warranty* lifetime of the transmission. However, most of us would certainly prefer that it last a lot longer than that. Therefore, to help insure this longevity, the tranny fluid (which is expensive) and the filter should be changed.

I was able to get the fluid at a VW/Audi dealer at around $16 a liter, and it came in single liter bottles. The BMW dealer would only sell it in 20 liter containers and it was about $28 a liter. The BMW dealers certainly aren't going to make it easy for the fluid and filters on these cars to be changed by anyone else but them. The Audi A-8 uses the very same transmission as does my 740i, and therefore uses the same Esso transmission fluid.

My 740i had 90,000 miles on it when I bought it, and probably never had the transmission fluid/filter changed. When I did it, the fluid was very dirty, but the filter and inside of the pan looked pretty good. Simply draining the pan, as I did, will not get all of the old fluid out since some of it will remain in the torque converter. However, this will get enough new fluid into the system to help, and I plan on doing another drain and refill in several months to get more of the, now diluted, old fluid out.

I don't know much about the transmission flushes I see advertised, that claim to replace all of the fluid, but I would not have that done on my cars. I would be fearful that the force of the fluid might dislodge something in the system. I simply have not seen enough evidence that this method is a safe route to go.

Dick Schneiders 1999 740i & 1991 525i