The reason for the annual or 24 month oil change is to deal with low mileage usage. Short trips, particularly in very cold ambients, are brutal on a vehicle. When I lived in -40, I religiously followed manufacturer's severe service recommendations, particularly for engine oil.

With a blend of highway and urban driving, I am now doing 12,000 miles in 15 months, so that is when I change it.

With respect to automatic transmission fluid, the original question, I wouldn't touch it, but that is just me. I haven't seen or read of problems with burnt fluid, more so failures of sensors and actuators, and those aren't going to be fixed by early fluid changes. With diffs, I wouldn't change them based on normal usage, but would do so if I was wading across streams (just as an example).

All that said, people are certainly free to change their fluids more frequently if it makes one feel better. After hundreds of threads on the subject, that is pretty much the bottom line. Do what feels good.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue