Originally Posted by gaydm.accord
I guess this dealership has shady practices.
Honda as of late has been plagued by automatic transmission failures in many models. Since many Honda trannies do not have a replaceable ATF filter, and since Honda does not recommend power-flushing their automatic transmissions, changing the fluid on a more frequent basis than the specified interval is an inexpensive way to keep contaminants from building up and to keep the fluid fresh. Keep in mind that only about half of the total fluid capacity can be drained out of the case when changing the trans fluid; the rest remains inside the torque converter.
Heat kills transmission fluid, and heavy duty such as stop-and-go city driving and/or hauling a lot of people around will create a lot of heat in the trans. Independent testing has shown that ATF-Z1 does break down much more quickly than the specified service intervals would have you believe, and I've seen a number of transmissions develop problems even before the first service interval is due at 60,000.
Often you should just go by the book, but in some cases Honda gets it wrong. For example, Honda's original recommended service interval for the Dual Pump fluid in '97+ RealTime 4WD rear differentials was found to be far too long, as the fluid would often break down so quickly that the diff would start making growling noises while turning as early as 30,000 miles. Honda eventually revised the service interval for Dual Pump fluid to 30,000 miles, and then later to 12,000-15,000 miles for the first service on '07+ CR-Vs. Another example is valve adjustments - Honda specified a valve adjustment interval of 105,000 miles for B20 engines so that they could advertise "no tune-ups required until 105,000 miles." Many of these engines sustained damage to the cylinder heads due to tightening valve clearances before even reaching 105,000 miles.
For the record, I change the ATF in my personal vehicle every 20,000 miles. Depending on model, I recommend trans fluid change intervals anywhere from 15,000 (for '97-05 J-series, '97-01 H-series, '98-02 F-series, '01-03 D-series) to 30,000 miles ('88-00 and '04-05 D-series, '90-97 F-series, '92-96 H-series, all B-, C-, G-, K-, L-, and R-series). For CVTs, I recommend changing the CVT fluid every 15,000 miles for '96-00 Civic HX and every 30,000 miles for all other CVTs.
$25 worth of fluid once every 18-24 months is a lot cheaper than a $3000+ remanufactured transmission.