Thoughts on Changing Transmission Fluid

[Brandon002]

Why not change the fluid at regular intervals to keep the fluid within spec?

So how long does a filter "hold wear materials" before the filter needs to be replaced? How long to the magnets accumulate metal particles before they need to be cleaned off?

You mean to tell me that a filter that collects wear items will perform as well as a new filter for the entire life of the transmission?

A new filter is going to perform better than an old filter. I saw my old filter after they removed it and it looked disgusting.

So maybe the fluid will last forever, but the filter needs to be changed and that requires replacement of the fluid.

And stop posting excerpts from an article on engine oil, you said it yourself, engine oil and transmission fluid are two entirely different animals.

You go right ahead and believe the "lifetime" claim on the transmission fluid/filter etc... I'll continue to change mine at intervals as it gives me piece of mind and COULD possibly save me major repair bills down the line.

[JCL]

Because you don't know that it is out of spec. With normal use, it won't go out of spec.

Filter is designed to last the life of the transmission. Magnets do not need to be cleaned off. If there is stuff stuck to them, great. That is what they are designed for, and where that stuff is supposed to be. Out of harm's way.

Do you think it was your fluid that was out of spec, or that your filter was partially plugged? Which problem did you fix? If the filter was so bad, you could have replaced it and put the same fluid back in. I agree that it is hard for people to bring themselves to do that, once they are already in there.

So you are saying that maybe the fluid will last forever? That is quite a shift in thinking.

Yes, changing the fluid could possibly save you money down the line. But we have nothing to base that hope on, except "because it seems right". On the other hand, we know it will cost you $400 every two years or so.

[JCL]

Originally Posted by Brandon002

And stop posting excerpts from an article on engine oil, you said it yourself, engine oil and transmission fluid are two entirely different animals.

That's interesting.

The oft-claimed reason for changing transmission fluid is because of improved lubricity, ie it will prevent wear. Taking all those particles out. Improving sliding and rolling friction between moving parts. In that sense, the engine oil article is completely applicable.

Agree that it doesn't cover the subject of the additive package in the transmission fluid, and the friction modifiers.

[Brandon002]

If youre against spending hundreds on maintenance every few years youre driving the wrong car. Like i said, you continue to run lifetime fluid and i will continue to service mine at intervals. I have always done this with all of my cars and i have never had a transmission problem.

[JCL]

Originally Posted by Brandon002

If you're against spending hundreds on maintenance every few years you're driving the wrong car. Like I said, you continue to run lifetime fluid and I will continue to service mine at intervals. I have always done this with all of my cars and I have never had a transmission problem.

I am a firm believer in preventative maintenance. I followed this philosophy for decades in the heavy equipment field. I apply it to my vehicles as well. Just not the automatic transmission fluid in my X5.

I've never had an automatic transmission problem either, since the restoration of a 66 Mustang that had a failed Cruisomatic transmission when I bought it. No problems after overhauling it.

I am not trying to talk you out of changing your transmission fluid. Each owner should do what they feel is right.

All I was pointing out is that many of the reasons given for doing regular preventative maintenance fluid changes on X5 automatic transmissions don't hold up to scrutiny. They don't have an economic basis. But not everything we do has to have a payback. Sometimes it just feels right.

[srmmmm]

I have no problem with changing the filter if the transmission feels "sluggish". But I will carefully collect the fluid from the transmission, strain it, and put it back in with the new filter and just top off with the proper fluid.

2002 3.0 X5 243,000 miles
2004 325i 108,000 miles

[upallnight]

Instead of listening to the marketing people from BMW you should follow the advice of whoever designed the trans, the engineers from ZF or GM .

I would guess that they would say to change the fluid at certain interval since as Engineers they know that to insure a long life for their products the fluid needs to be changed over a certain interval whether it be mileage or time.

[BMW_E53]

Well you'd never know. Most manufacturers say their transmissions are sealed units with lifetime fluid. This is what they told me when I bought my Tacoma two years ago. It also says on the tranny pan of our X5's that they are sealed units. Engineers from BMW and ZF have done hours of testing to advertise the fluid lasting a lifetime. It's just a gamble on whether or not to change the oil. That's all.

[Brandon002]

I thought I read somewhere that ZF recommends fluid maintenance on the X5 trans.

Let me see if I can find the article again.

[JCL]

Originally Posted by Brandon002

I thought I read somewhere that ZF recommends fluid maintenance on the X5 trans.

Let me see if I can find the article again.

It's been posted on this site.

ZF said they support the BMW recommendations as to service interval.

They also said that for severe service, the fluid should be changed. I think the interval was 10 years, and some specific mileage, from memory.

BMW is ZF's customer. They aren't going to contradict them. They are also going to take money from those who want to buy fluid change kits. They are not an independent bystander in this debate.

We also need to keep in mind that ZF built the basic transmission, but that BMW did the transmission cooling system, and the integrated controls that back off engine power during shifts to reduce clutch wear. Also the torque converter lock up strategy. All of those impact transmission life compared to applications of the same transmission without those features.