GroundRat

Drivers,

Have a 2003 525i E39 with automatic trans (American specs, 186K miles). Transmission operates fine; vehicle shifts with no issues. Vehicle operates in Germany and drives at 120-140kph on autobahn (75-87 mph). I tend to enjoy the autobahn vs. race the autobahn.

Do I/Should I change the transmission fluid either with a complete system flush? Or should I do a filter change and replace the fluid until the system is at capacity? Previous owner did not keep maintenance records.

Been told by some local motorheads that due to the age of the vehicle, if it's not broke, don't fix it. On the other hand, I do like the vehicle and don't mind keeping until it dies.

Suggestions and advice welcomed. Thanks!

V/r,
GroundRat

seanjordan20

I would just do a filter and fluid change. I've always been told never do a flush on a trans just keep it fresh around every 50k

Goz007

100% change it(make sure u use the correct oil)check the color tag on the trans as this will indicate which oil goes in

GroundRat

Thank you for the response. If you don't mind me asking, what would you say to the local mechanic who advises against the fluid / filter change? His reasoning is that a total fluid and filter change would remove some of the deposits that provide friction for the transmission to work. The removal of the deposits might cause the trans to shift erratically since new fluid doesn't have the sediment accumulated through years and years of use.

The trans is still operating fine at this point. Even when I use the "manual" option to shift the vehicle accelerates w/o a problem.

V/r,
GroundRat

Goz007

Well I'd be finding another mechanic that is confident on replacing it(u are best finding an automatic transmission specialist)not only is there a filter there are also magnets that will have accumulated debris on them, as long as u use the correct fluid for the transmission tag color, I'm sure u will have no issues, I've just changed the fluid&filter in my 2001 530i & the oil & filter was very dirty & the magnets were covered in metal, on the initial test drive I thought oh my the gearbox is no good, but after a few hours of driving it around the car has never driven(changed gears) so good....my car has traveled 300000kms

seanjordan20

A drain and fill is not a total fluid flush. You're only replacing around 6.5 liters. If you're wanting it to last do the drain and fill.