[sauropod]

"As a general rule of thumb, newer transmission designs are sealed for life," said Tim Miskotten, who leads North American business for ZF AG, the German company that is the world's largest independent transmission maker. ZF supplies gearboxes to Ford, Audi, BMW Jaguar and other leading automakers. "You don't need to change the fluid in the normal life of a vehicle," Miskotten said.

I don't think I believe this. Engines consume oil. I would assume they consume XMSN fluid also.

I own 2 high mileage cars. I have definitely noticed a "lag" in the auto XMSN even when the oil has been changed (i use synthetic).

Need more proof than what some German with an agenda provides.

[Signalman]

I’ve got a 2003 Jag, purchased new in 2002, that just passed 104K miles. The tranny is sealed (Jag says do not change the fluid) and uses synthetic ATF. It shifts as smoothly today as it did when I first bought it. I tend to believe that it’s better not to mess with the tranny fluid...with a few exceptions.

If you frequently tow a trailer (that puts a lot of strain on the transmission) or if you drive for an extended period in a hot climate (Phoenix from June-August for example). In those cases, I would change the fluid every 30K-60K miles.

[Neidermeyer]

I own 2 high mileage cars. I have definitely noticed a “lag” in the auto XMSN even when the oil has been changed (i use synthetic).
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Minor transmission problems like your “lag” are usually due to slightly dirty or sticking components... I have used “AUTO-RX” to clean a Mercedes tranny (slow upshifts when cold) and a Taurus (AXOD tranny) that slipped completely out of gear in hard left turns ... The stuff is magic ,, cleans slowly and completely ,, drove both cars another 100k afterwards ... Follow the advice on the website and have the fluid and filter completely changed by a transmission specialist after treatment. http://auto-rx.com/transmissions.html

[Vendome]

Sure.

And the sealed bearings on your wheels need periodic service. /s

[Safetgiver]

Engines consume oil. .... I don’t believe we are talking engines. We are talking transmissions here.

[OKSooner]

Engines have combustion in them; transmissions don’t. After awhile (3000-5000 miles or so?) those little microscopic particles of dust become a problem in the crankcase, along with maybe even some microscopically small fragments of steel and other stuff. That’s why your engine has an air filter and an oil filter.