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Originally Posted by ard
Did not see a 'cooler maintenance' in their schedule...nor do I think such a thing exists. Clean the fins??? that kind of "maintenance"?
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Since heat is the enemy, maintaining the transmission cooling system is key. The thermostat could be replaced, the cooler and lines could be inspected. I wouldn't expect to see it in the BMW schedule, but you already have the schedule; you asked what type of maintenance would have the biggest impact in extending transmission life.
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Originally Posted by ard
If you can show me ANY data that supports a "100,000 mile, unlimited years" lifetime on ANY ATF, you get a beer.
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How about transmissions over 200,000 miles with the original fluid? Real world data? There are posts on this forum. Here are a couple that I came across quickly.
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Originally Posted by a regular poster
2001, 118000 miles (189000 km). Still going strong. Not much problems and failures.... The original oil is still in the tranny...
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Originally Posted by another regular poster
I have 115,000 miles and I have the original oil in the tranny as well. I have never heard of a transmission on a BMW X5 going out because of bad oil. .
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If those tranmissions can go those distances on the original fluid, doesn't that suggest that the factory fill fluid can last just fine?
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Originally Posted by ard
This is an interesting argument- although I'd need to know where the drain is- and if the valve body is drained, the TC, or what
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I assumed draining the fluid through the pan, the valve body being drained when the filter is changed, and the torque converter not being touched.
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Originally Posted by ard
How long (will the fluid last)? BMW says 'no time limit' or 100k.
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Life of the transmission, whatever interval fate and non-fluid related failures cause that to be.
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Originally Posted by ard
I am truly surprised at both the argument that a fluid change is a risk (afterall, BMW does recommend one, so how can it be a risk?), and the argument that ATF has virtually no life limit....
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The entire point was that doing a transmission fluid change incurs a risk. If there was no risk, it would make complete sense to do it regularly, given that we agree that clean fluid is in general a good thing. It can be a risk whether or not BMW recommends doing it. Compare it to surgery; you can often repair a problem with surgery, but surgery is generally not without risks. It is a tradeoff of likely benefits versus potential downside. I also do think that ATF has a life limit, just that it is longer than the MTBF (mean time between failures) of BMW automatic transmissions. All this would change if we had posts about regular transmission failures involving burnt fluid or clutches, at mileages that correlated to having missed fluid changes.
Cheers
Jeff