Let's talk Transmission Maintenance...

[FSETH]

Originally Posted by JCL

My lack of support for changing the fluid is not because "BMW said" but rather because I see little benefit to changing it, and a small but real risk. The risk of damage is slight, but it exists. At the same time, I think that the transmission is likely to fail from non-fluid related causes prior to the fluid degrading to the point that it causes a transmission failure itself...

There are members here with transmissions far beyond 100,000 miles, on the original fluid. What that really means is that other things haven't broken yet, and the fluid has just soldiered on.

This entire post by JCL was great, IMO, but the above comments stood out the most to me. I appreciate you pointing out that fluid changes DO come with a small, but real risk. I think some people have a hard time believing that. What you say makes sense to me personally, but then I don't have any hard data to back it up. I take your word for it as someone who seems to have extensive knowledge and experience in this arena.

I also agree that there are simply way too many 100,000+ mile X5's rolling around out there that are on original transmissions and fluids for me to think that a breakdown in fluid is the main cause of BMW trans failures. For every person with over 100k miles on original fluid there is another who's trans failed under 50k miles. It seems as if the age of the fluid is inconsiquential to the life of the trans in most cases.

Quicksilver also made a good point that people are going to do what they want to do when it comes to this issue. At the end of the day, do what makes you happy. Just dont think that changing the fluid is going to prevent trans failure and realize that there is a small risk in doing so. It is not always that new fluid = better in an auto trans.

For what it is worth, I have an 02 4.4i with 109,000 on the original trans and fluid and it runs fine (knock on wood). I also have an e36 325i with 303,000 miles on the original automatic trans. I bought that car with 100,000 and have changed the fluid 3-4 times over the past 7 years or so. Started slipping a little between 2-3 gear about 60,000 miles ago, but it has been soldiering on.

I would be curious as to what the average lifespan for a BMW automatic transmission is these days anyway. I bet it isn't that much over 100k. BMW probably doesn't see any reason to recommend changing the fluid before that mark because they know that the original fluid will last the average trans lifespan anyway.