Asked by Nov 20, 2008 at 01:43 AM

Question type: Maintenance & Repair

Let's really sort out what the deal is with routine maintenance in regards to transmission fluid and its filter:

I tried to get a shop to change my filter and fluid...they said they would just change out the fluid and NOT the filter, but instead reverse-flush the filter and reuse it. The other ASE certified techs nodded their heads and said same thing.

On the other hand, my pal changed fluid without filter change on his car...and said transmission was still he got new filter and voila! It worked perfectly.

Seriously...what is the deal?? Change fluid WITH new filter OR change fluid and reverse-flush the old filter and reuse?? END this myth once and for all!!

7 Answers


OK..this gets a little complicated. Automatic transmissions operate on fluid pressure, friction, bands and a LOT of valves. Initially, the fluid is clean and things work well. As the heat and mileage grow, the fluid thickens and the filter clogs which affects the performance of the tranny. The belts and other components will allow slippage which often lead to transmission failure. When a tranny is high mileage, 100K or greater in miles, many service related shops refuse to service them. Often, after flushing the unit, changing the filter and fluid....sometimes they FAIL. In return, the customer holds the shop accountable for a trannyin which they had no fault in it's failure. I don't see why the fluid was changed but not the filter? Clean fluid circulating through a contaminated filter leads to dirty fluid. Maybe they didn't have the filter on hand or wasn't willing to drop the tranny pan to replace it? Maybe they were looking at the mileage and determined it "risky" and unwilling to be responsible for the tranny if it failed? I can't provide an exact answer regarding the subject. There are folks with more expertise than me on this; there could be a better answer than mine.


IMO, you're dead on on this one... One thing that was said stuck out. "was still slipping"... As in it had problems when he brought it to 'em. My guess is the shop didn't want to touch it in the first place, and only put new fluid in on the off-chance it was varnish related... That's assuming you told them it was slipping when you brought it to them. That being said I'm not a tranny expert by any stretch of the imagination,but there are a few questions that will help the experts answer your particular question. 1)What is the recommended service intervals for your transmission? (There is often one for changing just fluid and another for both the fluid and the filter) 2) Heck tell us about your car... Mileage, make, model... If it's a sedan, do you have a bumper hitch...


I also agree with what Logan said... i work in a diesel shop and its a totally different thing with there transmissions... but as far as automobiles the reason is bc they dont want to be blamed for something as expsensive as a transmissions...


2004 Dodge Stratus, now with about 98,000 miles. I have a Haynes manual, and it does have the service intervals for fluid AND filter...and change more frequently if in city, and frequent short trips. I don't remember if I told the shop that the trans was already slipping, but it was like that when we got the car. It being a former rental car, who knows how abused it was. Also, there's a proper tranny break-in cycle, that probably wasn't performed, but that shouldn't be a major playing factor right? No bumper hitch, the car has never been loaded down heavy, and is very empty of any excess cargo. I keep it clean inside and out... But, specifically, the gears slip from upshift 2 to 3, and going 20 mph to 30 mph. Or if I'm hard accelerating, and I let go of gas, the trans will JERK into the next gear...JOLTING the whole chassis...this makes me nervous, but it IS a Dodge... So, in light of this, should the filter be changed along with its trans fluid? Will this help with shifting? There is smooth shifting from 1-2, and 3-4, but just that 2-3.


As I said I'm not too keen on trannies, so I'll say take it too a tranny shop (reputable one in your area), tell them your issues and see what they say... I have a few theorries but they address half your issues at best so I'll keep 'em to myself instead of pointing you in the wrong direction. When you find out whats wrong, let us know what you found out.


It would be a very good idea to find another Dodge Stratus of the same year and give it a test drive. If it performs in a similar manner as yours, that could be a routine habit of that particular tranny. If you perform the test drive and discover the performance is acceptable in the borrowed car, you have transmission issues. Those chrysler 4 speed automatics are not the most refined could be performing normal. If you decide there is an issue, it's a crap shoot. Cleaning up the tranny might improve the performance; don't be surprised if it gets worse. I'd avoid a tranny shop because they will ALWAYS try to talk you into a rebuild or remanufactured tranny. Both very expensive. If you must change the tranny, locate a salvage tranny with low miles.


Well, I think new fluid and filter will be forseeable in future. However, the tranny DID do this when we first got, I think it's the nature of the beast... But I can't help but think on a microscopic level: every time the trans JERKS...there are pieces of metal that break off...and the more that happens, the more the filter gets clogged... I'm a TOYOTA FAN...always have...always will be...the original 1982 transmission, ONE fluid and filter change...and it runs SMOOOOOOOOOTH!!

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