Jaxbeachbmw

Hey Everyone,

What's your advice on transmission fluid? When should I change it? What should I use, etc.? Thanks...I appreciate the expertise.

locomotiveBart

BMW used to say lifetime, now they have changed to 100k miles. This question has about 1000 answers so just pick the one you like and run with it. For what it's worth, I changed the fluid in my old 325i at 127K and it looked nearly perfect. On my current 2 5 series cars, I plan on changing it before 100k hits but not too long before.

rctmthouse

https://5series.net/forums/topic/115...id-comparison/

B_Schnell

I was just at Crevier BMW today and asked a tech to verify what Trans fluid they use. I told him I checked a Crevier invoice from 2006 when they replaced the trans oil for the cylinder head valley pipe gasket(where engine and trans are removed) and the invoice said they used Pentosin oil. The car had about 35K miles at that time now I have 72K. The tech said that must be typo from advisor as they always use the ZF OEM oil. They only get it in large 40 gallon or so drums, so not set up to sell liters to the public, although he said they can and do for customers to come in but not sure on price. One thing that the tech said is that they only replace what comes out, which is about 3 to 4 liters and they do NOT vaccum flush all the old fluid out. Reason is if you do replace ALL the fluid, then the transmission may start slipping. Even though the old oil looks black and the new oil is amber color, doesn't matter. He said do not replace all the fluid as it may cause slippage. I assume is due to resulting viscocity change and how the tranny breaks in. I did trans pan and oil replace about 1,000 miles ago and went with the Pentosin oil about 15 bucks a liter from World Impex, I drained about 3.5 liters and guess must have been over a liter that leaked out as I replaced about 5 liters. So far no problems and trans is running smooth. there is a great trans pan and fluid replace posting in the DIY section of the forum. Lots more info