My sister keeps getting told that her transmission needs to be flushed and she's asked me if I think she should get it done, but I'm hesitant, and not very knowledge on the subject anyhow.

My dad had his transmission flushed in a chevy blazer and soon after the tranny died. My sister got her's flushed before - the first time was with her Honda Accord - not long after the flushing the transmission went out; same thing happened on her pontiac.

I've never heard of a positive story with flushing the transmission - can't you just top it off and keep running?



[Edited on March 16, 2009 at 5:26 PM. Reason : ibtmtg]

3/16/2009 5:25:21 PM

IBTROTF

95 blazer
97 accord
not sure on the aztec (early 2000's) - they didn't make them long, I think

3/16/2009 5:32:25 PM

I have my transmissions flushed every 30k. Only with factory fluid (not dextron and a friction modifier - like some shops use). Never had a problem.

If you maintain your vehicle, it shouldn't be an issue. If you neglect, I dunno.

I do know that I had my really old 100k+ car flushed and it's doing great too.

You could always have the shop guarantee in writing that the transmission won't fail in 1yr/12k and see if they agree to it. (they won't).

Doing a drain and fill (3 quarts or so every drain) would be the gentle way of doing it.

[Edited on March 16, 2009 at 6:16 PM. Reason : most of the people in here will say not to do it on an old neglected car.]

3/16/2009 6:13:53 PM

thanks. it's not too old (less than 10 years) but definitely not well maintained

3/16/2009 6:19:01 PM

Quote :

"most of the people in here will say not to do it on an old neglected car"

3/16/2009 6:23:57 PM

here's the theory. if you've neglected your tranny, it's already deteriorated to shit. it's held together by the goo that used to be tranny fluid. draining it will have mixed results. if you make a habit to do it at regular intervals, proper changes are good.

[Edited on March 16, 2009 at 7:57 PM. Reason : if it's an auto, I WOULD change the fluid filter regardless]

3/16/2009 7:56:35 PM

the problem lies in the person doing the flush, their procedures, and the machine used. it CAN be done properly/successfully, but you're taking a pretty damn big risk on those factors unless you really know the person doing it or the shop. even then, there's still the risk of that little bit of shit hanging on that dislodges down the road, clogs the cooler, and boom it goes.

i, like most here, am of the opinion that anything that's had very long intervals between changes or otherwise has a lot of miles is better left alone in terms of flushing due to the risk of stirring up/loosening sludge that will later wreak havoc in the cooler, pump, etc. just do a basic fluid/filter change and roll. optmusprimer will disagree with most of this, and a lot of what he says makes sense, but i'll let him post his thing if he wants.

3/16/2009 8:05:37 PM

i agree with ^bbr. if the vehicle has less than 50K miles, then change it. if it has more and the transmission has never been serviced, don't change it. however, make sure the fluid level stays full. make sure you know how to check transmission fluid level also. it still boggles me the number of people who own a car but don't know how to check the damn fluid.

3/16/2009 8:21:51 PM

^^What he said.

3/16/2009 8:27:42 PM

^^well, with the world of sealed transmissions it's going to become a hell of a lot more common.

3/16/2009 8:31:57 PM

They flat out refused to flush my trans fluid on my VW.
It is possible, but a lot of work because of the 'sealed trans'.
I thought is was funny they turned down $300 for a couple hours work.

Now it is slipping at 75k miles, and I hope it makes it to 90k.
Stupid VW. Stupid me for getting an auto (again).

3/16/2009 9:41:46 PM

lucas mucus!

3/16/2009 9:44:31 PM

i say an old neglected car needs it the worst, but any car can benefit from it.

but at over 200 bucks, only the worst of my fleet will get complete flushes. and my towing vehicles.

3/16/2009 10:06:04 PM

I agree with the majority in this thread.

Also, if you avoid automatic transmissions, this becomes a moot point.

3/16/2009 11:36:02 PM

i'm still a firm believer not to change it in a vehicle that's never been changed. however, just found out today that the fluid on my Dad's jeep cherokee has been changed once at 225K miles. it now has 400K on it still on the original transmission and it shifts like it's brand new.

3/17/2009 8:59:53 PM

I don't agree with flushing a high mileage transmission. It's gonna definitely wreak havoc with it. Seen it several times. A lot of the friction materials can and will come apart as well...not just all the old shit that breaks loose and clogs the cooler and toasts the tranny. Good auto tranny fluid has a high level of detergency and will clean the hell out of anything that's in there.

3/17/2009 9:13:26 PM

More information:

The aztek's transmission was rebuilt & flushed at 50k miles. it now has 80k miles.

according to previous posts, I'm going to tell my sister to get it flushed, unless someone says otherwise soon.

3/17/2009 9:23:44 PM

For those who recommend against flushing; do you also recommend against doing a couple of drain & fills to swap the fluid?

3/17/2009 9:31:48 PM

Done that quite a bit. How I kept my mom's Mazda 626 tranny in one piece as long as I have. It's a Ford transmission famous for shitting the bed. So bad at burning fluid, that I would do it every 12k miles. Didn't get the first one until after 75k. I gradually got to the point where I flushed it completely with Amsoil ATF. No problems.

3/17/2009 9:36:05 PM