trans fluid - 2003 X5 - lifetime? manual says 100K

[c4racer]

I just picked up a 2003 4.6is and it is nearing 100K miles. The trans fluid has never been changed. I did a search and read a lot of the pros and cons and I was leaning towards leaving it alone. But the BMW factory service manual that came with my car and applies to all 2003 X5's specifically does say to change the fluid at 100K miles, along with the spark plugs.

So what is the basis for the claim that BMW calls for "lifetime fluid" - is this perhaps a BMW NA recommendation to avoid potential problems with people not doing the change properly? Because it seems when BMW manufactured the 2003 X5, changing fluid at 100K was part of the intended service requirements.

[Weasel]

The high mileage fluid changes are always iffy for the simple reason that the clutch packs in the transmission will wear no matter what, and the clutch material gets suspended in the fluid and alters the viscosity and friction profile. When you change the fluid the worn clutch packs are more prone to slippage and it can cause a transmission failure earlier than if left alone.

On the other hand, the fluid will break down slowly over the years and after a certain point it will be less efficient as a lubricant and a hydrolic fluid. It really is a lose lose situation, but the wear on the clutches causing slippage will surface faster after a fluid change than any problems caused by not changing the fluid. (in most cases)

[chigga]

dang... and i thought changing it was a good thing. I had mine changed recently, i saw the waste that came out... BLACK!! really BLACK!! and it was $500... u telling me i should of gotten a rear bumper cover instead?

[dkl]

Originally Posted by Weasel

The high mileage fluid changes are always iffy for the simple reason that the clutch packs in the transmission will wear no matter what, and the clutch material gets suspended in the fluid and alters the viscosity and friction profile. When you change the fluid the worn clutch packs are more prone to slippage and it can cause a transmission failure earlier than if left alone.

On the other hand, the fluid will break down slowly over the years and after a certain point it will be less efficient as a lubricant and a hydrolic fluid. It really is a lose lose situation, but the wear on the clutches causing slippage will surface faster after a fluid change than any problems caused by not changing the fluid. (in most cases)

Your reasoning makes a lot of sense. However, shouldn't the filter have caught 90%+ of those clutch materials as well as any metal shavings? In any case, I'm more worry about the filter getting clogged up, then getting bypassed...which would accelerate the wear rate. That's the only reason why I dropped the pan, changed the filter and just replaced whatever that got drained out of the pan, rather than a complete flush of the system.

Since it's a lose lose situation as you have indicated could very well be the reason why BMW keeps flip flopping back and forth with regards to its recommendation on the transmission fluid change

So...when BMW say transmission fluid "change", how does the dealer go about doing it? Do you have the equipment at the dealer to get all the fluid "flushed" out, including those in the torque converter? Or does the "change" simply means a pan drop, filter replacement, and refill of the pan?

[c4racer]

Originally Posted by Weasel

The high mileage fluid changes are always iffy for the simple reason that the clutch packs in the transmission will wear no matter what, and the clutch material gets suspended in the fluid and alters the viscosity and friction profile. When you change the fluid the worn clutch packs are more prone to slippage and it can cause a transmission failure earlier than if left alone.

On the other hand, the fluid will break down slowly over the years and after a certain point it will be less efficient as a lubricant and a hydrolic fluid. It really is a lose lose situation, but the wear on the clutches causing slippage will surface faster after a fluid change than any problems caused by not changing the fluid. (in most cases)

Yes - I've read that reasoning here before. But I guess my question is what is BMW's official position and what is behind it? When the 03 X5 was made, BMW recommended a 100K fluid change. I am under the impression that US BMW dealers are now telling customers the fluid is lifetime. But that is not what my service booklet says. So are the dealers getting this lifetime fluid recommendation from the actual factory as an official update, or did they come up with it on their own because they ran into some issues with complications from a fluid change causing issues?

And if the fluid change is $500, I am leaning towards keeping that as a downpayment on a rebuild if there is really no data from BMW and the trans mfgr to suggest a fluid change will provide any longer life. Should be somebody around in CA that can rebuild a ZF for $2500 or so.

But I do find it odd that BMW would change their position on this service. And I also find it rather coincidental that other car makers like GM that use the same trans (not to mention GM made the trans) are using the same 100K fluid change interval that BMW used to recommend. That also suggests 100K is not "high mileage", since that is the recommended fluid change interval.

[c4racer]

wow - I got quotes from both Dinan and an indy shop, and both want about $550 for it. 3 hours of labor at $120 per hour. It cannot take them 3 hours.... Anyway - if I do it, will probably just do it myself and do a simple pan drop, replace filter and leave aprox 30% of the old fluid in there. If there is something to the viscosity theory that may be better than replacing 100% of the fluid.

[dkl]

An indy shop charging $120/hr for labor? Mind as well just bring it into the dealer for that kind of money. I had my indy did fluid change on the transmission (pan drop, filter change, refill), transfer case, and both differentials for about $600 last year.

If you decides to do it yourself, then it may take that entire 3 hours or more unless you have access to a lift. And if you don't have access to a lift, it'll be a messy job

Good luck!

[Werewolf]

Lifetime refers to the 'lifetime of the vehicle'--which I guess is a 100k. These auto trannies were a design weak point, expected life 100-150k I think.

The shop labor rate seems a bit rich. I am guessing you're in the bay area? I would pay a good independent no more than 100/hour

[c4racer]

Originally Posted by Werewolf

Lifetime refers to the 'lifetime of the vehicle'--which I guess is a 100k. These auto trannies were a design weak point, expected life 100-150k I think.

The shop labor rate seems a bit rich. I am guessing you're in the bay area? I would pay a good independent no more than 100/hour

correct - bay area

I would just do it myself. If it takes me 3-4 hours, that's just fine. There is nothing complicated about it. Actually the indy confirmed what they do is drop the pan and replace the fluid that comes out that way only, which is about 2/3 or so. And they do not recommend the service since BMW does not recommend it, but they do it when people specifically ask for it.

I read a bunch of other forums from 7 series owners, and did not come to any better conclusion. good arguments from both sides. But I am leaning towards sticking with the BMW recommendation, because there is a good chance that the trans will fail at some point regardless if the fluid was changed or not. And I don't want to speed up the process. When it goes, I will get it rebuilt. Hopefully not, but I figure it is going to happen. My neighbor just lost the trans in his 2000 740iL at 150K miles. I figured that was pretty good given the use cycle - mostly city driving by a lead-foot My 4.6is has seen almost all highway driving for the last 45K miles, which is pretty easy work for the trans. So there is some hope mine may live longer than 150K, although I am not banking on it.

[Werewolf]

How do you like the S4 with the v8?

I've seen some tempting used s4s down in SoCal but I am a bit of leery of maintenance and reliability...but 340 bhp sounds good