lots of misinformed advice on trans fluid changes. most newer cars discourage you from changing trans fluid. lifetime fluid. trans fluid is subjected to less harsh conditions compared to motor oil. does not see high combustion temps and contamination from gasoline due to ring blowby. i like the full fluid exhange route and i also prefer changing filters if they are available. do both, probably the only time you will do it. unless you plan on driving 150k or 200k miles on car.

Really? Lifetime fluid? That sounds crazy. I have become a believer in regular trans service.

My current van is a 2000 dodge grand caravan with 145k and going strong. I attribute the trans service (new fluid & filter) to this. Prior, I had ruined three chrysler/dodge transmissions (an '89, once, and '94 twice) by neglecting the trans.

Appreciate the replies guys. I keep my vehicles for a long time (average 10 years) so preventive maintenance is an important issue with me. The fact that GM has a fluid change in its maintenance schedule excludes the lifetime fluid philosophy. I'm also a firm believer in replacing filters whenever you change fluids. I note that the flushing method for trannys merely "backwashes" the old filter which is then left in place. This has convinced me go the tried and tested method of draining the torque converter and tranny box and installing a new filter. Does anyone on the list use a transmission fluid additive thats supposed to "recondition" seals etc. Never use them myself but some of the old car guys I chum with swear by a few of them. Just curious on this one.
Cheers and thanks: Bucky2

i had a 96 intrepid. got it from original owner at 90k miles. 4yrs old. i did change trans fluid often. hit 150k miles and sold it. shifted fine. pulled lower radiator hose the first year and brown stuff came out. actually looked kinda milky. hmm. never overheated and never used coolant. maybe it had some kind of stopleak in the coolant.

funny, my toyota manual says 'inspect' every 30K. I just had my car in and opted out of the 60K reccomended service...a bunch of checks and an oil change and tire rotataion and filter changes for $379...did not include ANY fluid changes like tranny or coolant......thats extra if needed. I instead opted for the 'free' fluid check with an oil change where they supposedly can check the fluids (from coolant to tranny to brake to power steering) and definitively tell you what needs changing. To my suprise they said the fluids were all fine...even at 60K. So long as it keep my extended warranty in effect....which it does...

The dealer does do the tranny flush with the machine but they said it was not warranted at this time.

From what I have read about that flush...if you get every 30K it should never be a problem but if you wait till 90K it could do more harm than good...you'd have to google to get the specifics...something about metal shavings being pulled places they should not go....? IMO, with a car out of warranty I would not chance it unless I have had it done every 30K or so....and since the dealer said my fluid was good and have not yet had it done....and my warranty ends at 75K so...I'll likely never have that machine do it...

most newer cars discourage you from changing trans fluid. lifetime fluid. trans fluid is subjected to less harsh conditions compared to motor oil.

+1

Just dropping in while looking for information on draining radiator in a 2005 Chevy Colorado Pickup... but this thread touched my other unanswered question, changing automatic transmission fluid.

I had my 2004 Subaru Forester in for a warranty check on corrosion - of course the dealer shop looks for things that need to be done. This car has about 55K miles on it and has been very reliable. The mechanic reported several DYI things and the need to change the transmission fluid. This was recommended a couple of year earlier when I had the car in for new tires.

The Subaru Forester manual doesn't call to transmission fluid change (I'll take another look, maybe it does at 100K miles) - I chock it up as just high profit dealer (not necessary)service and don't get it done. That said all my other cars and pickups over the past 25 years have had manual transmissions, so the subject never came up there...albeit some shops may want to change the manual transmission oil too.

The main difference between older and newer automatic transmissions is the lock-up clutch. During a goodly portion of time on trips with the lock-up, the torque converter is locked, and when locked. it does not add much heat to the fluid. In older transmissions, the primary source of heating was from losses in the torque converter. With the converter locked, the remaining heat sources are gear and bearing losses.

It is my opinion that the lockup clutch contributes to exending the life of the fluid.