Auto gearbox doing odd things

[dkl]

Just an FYI - I replaced my filter an fluid at 80k miles. Currently at 133k without issues

[80stech]

If you want to save money and the enviroment, it would be a lot more relevant to change engine oil according to the service indicator, maybe filter at every second change, than to try to go forever on the trans fluid. @andrew, magnet is in pan from factory

[Crowz]

Lets look at what the people who make the transmission that's in the 3.0 x5's say about the transmission. Since its a GM transmission and not a BMW transmission or a ZF trans.

50,000 Miles (83 000 km)
Change automatic transmission fluid and filter if the vehicle is mainly driven
under one or more of these conditions:
– In heavy city traffic where the outside temperature regularly reaches
90F (32C) or higher.
– In hilly or mountainous terrain.
– When doing frequent trailer towing.
– Uses such as high performance operation.
If you do not use your vehicle under any of these conditions, the fluid and
filter do not require changing

The tsb's put out later by GM recommend changing the fluid at 75,000 miles no matter what if any signs shifting issues occur.

Trans fluid doesn't just get "dirty" and cant just be filtered to make it suddenly "new" again. It breaks down over time. The shift modifiers are one of the first additives to go.

The tricky part isn't if putting new fluid in is a good idea or not. That's a fact. Anyoen that believes otherwise hasn't rebuilt transmissions before. I have.

The tricky part is finding the right fluid as time goes by. Companies change fluids to meet newer designs as time goes by. Basically given enough time its impossible to get your hands on the "correct" fluid to go back in there when you go to do a fluid change.

Sure the bottle says "backwards compatible" but that's just marketing speak for "we don't have that exact fluid anymore but we want your money so use this".

IF you can get the correct fluid then changing the fluid is a no brainer. If you use the wrong fluid you can do more harm than good.

Driving conditions also effect fluid condition and service life. If you drive easy enough to never overheat the fluid it doesn't break down much. But even with this lower temp environment it will break down over enough time.

The ultimate service for a transmission in my opinion is as follows. Again this is from my experience and not gospel. Fluid breaking down over time is fact though.

70,000 or so change the fluid and filter.

150,000 change the fluid, filter and valve body and all of its parts.

230,000 change fluid and filter.

300,000 miles change fluid and filter.

375,000 miles change fluid, filter and valve body.

After this point its probably about trans building time for most folks. The clutches should be about shot.

You can keep doing the fluid and filter and valve body swaps but the clutches are going to start slipping after that for most people under heavy loads.

[80stech]

[andrewwynn]

That's great detailed advice very helpful to see the detailed info from the maker that basically puts the * explaining if you use the car as a as soccer mom you could get away without changing


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[Crowz]

Also one last thing to keep in mind. The company you buy your vehicles from WANTS it to fail after its out of warranty. This makes them money and gets you to buy a new car. Selling a car that last forever would be incredibly stupid for them to do and they know this. Most car companies would be out of business in no time.

A well designed car from a manufacturers standpoint is a car that can go a million miles but dies in 5 to 8 years TOPS. They want you to get all the miles you want out of it but they want to sell you a knew car in under 10 years. Any longer than this and it hurts their profit margin.

BMW has a minor upswing in this formula seeing as new = bling factor. The ones buying new don't want to be caught dead in "last years" model/design.

GM, Dodge, Ford, etc just want to sell cars and the people buying them are not as interested in buying a new one just to have what is out "now".

Anyways I never take a manufacturers recommendations for long term ownership since its not in their best interest to be honest about it