My car has 15 year old tranny fluid with 150k mile

[01rangerxl]

I don't think changing fluid on a high mileage transmission is an issue by itself.

I think it COULD be an issue if...
- The trans is already having problems, particularly problems that are chewing the clutches up
- The wrong fluid is used
- A flush chemical is used and there is a large amount of debris in the transmission

And in many cases it is simply too little, too late. Trans was on its way out, which is WHY it was finally getting a fluid change, and the fluid change didn't save it.

I have changed trans fluid on a number of high mileage vehicles. Personally, on changes I have done myself, I have never seen the correct, new fluid uncover a problem that wasn't noticeable before. This includes vehicles like my 1995 Explorer and Jeep Grand Cherokees with over 150K.

 

[jk_636]

Pull out all that old, nasty and worn fluid and replace it with fresh ATF. I like Royal Purple, but there are many good options out there.

Don't buy into this nonsense of "lifetime" fluids or mechanics that tell you never to change it. That's what I would say to if my livelihood depended on selling transmissions...

 

[wtd]

So what is the difference between an exchange method of changing transmission fluid where you let the cars transmission pump circulate the old fluid out while bringing in the new fluid compared to a flush or is people calling this the same thing?

Wayne

 

[dlundblad]

I believe during a flush, the transmission is hooked up to a machine that uses pressure to push the new fluid in and the old fluid out. I want to say it gets nearly all the fluid too.. even the stuff in the clutch.

A cooler line flush just makes the transmission pump do all the work. Just disconnect the cooler line that comes from the transmission to the radiator and have it flow into an empty jug. Turn the car on and let it pump it out while someone else is pouring fluid into the fill tube at the same time. I think this method gets most of the fluid, but not not all of it. It still gets more than a pan drop though.

 

[OceanRuns]

I have personally experienced altered shift characteristics when doing a drain/fill on very old fluid. This isn't to say it is bound to happen, it may be that it's rare.

In my case I had a 1980s Toyota, fluid looked worked. I did a drain, fill, and replaced the filter (a screen).

Prior to to the drain, the vehicle wouldn't shift until it hit higher RPMs than seemed normal.

After the drain/fill, the shifts occurred at lower RPM, but, the shift from 1st to 2nd was quite harsh. Out of the two options, I'd have preferred the way it acted before.

I ended up selling it shortly thereafter (full disclosure included).

 

[eljefino]

I'm in the camp of "change it already".

I rescued a cutlass ciera that had a thoroughly plugged filter and couldn't make pressure, which was slipping the clutches, which were shedding silt, which was clogging the filter...

Got it just in the nick of time.

Ideally (to read some people) you could/ should change the filter while somehow keeping the old nasty silty sheared down fluid. Nuts to that, I say. Drop the pan the way the engineers intended and put in enough new fluid to make it work. Depending on what stays in the torque converter you'll get half new. I bet you'll like it.

But like the Hatfields and McCoys, you'll never get a consensus.

 

[mrbamathews]

Here is the truth:

Transmission sometimes do give up the ghost shortly after having fluid changes. This generally happens on transmission with high mileage that would have failed at some point regardless. Changing the fluid simply speeds up the process in some cases. But the reason is generally not because of junk clogging the valve body, solenoids, etc...

The problem is generally high mileage automatic transmissions have a lot of clutch wear. The friction material worn off the clutches is now suspended in the fluid. The transmission still uses that friction material in the clutches to prevent clutch slipping. People come along and dump out the old fluid (with a lot of friction material in it) and replace with new fluid. The new fluid has no friction material and a lot of fresh detergent. Shortly after the clutches start slipping and next thing you know the car needs a trans overhaul.

Bottom line, if the mileage is super high and the fluid is very old do not "flush" the transmission fluid. Only drain and refill (generally only changes 1/2 the fluid). Then if possible use a scan tool to reset the transmission shift adaptions so the electronic transmission controller can learn and adapt the best shifts with the fluid change.

 

[mballard70]

Mrbamatthews FTW! Excellent and sane explanation. Thank you.

 

[burchster13]

My wife bought her first car an 89 Lesabre in 09 with 150k. The trans had never been serviced so I just dropped the pan and changed the filter. Did it again at 170k. Now at 199k I'm using it as my commuter about 70 miles a day all highway a little stop and go. I'm thinking about doing it again. Now we did this to my father in laws 99 Taurus at 150k and now it needs a tranny

. I don't know if this helps but I wouldn't do a full change.

 

[mrdctaylor]

FWIW, I agonized over this decision with the vehicle my parents gave to my daughter. Story:

My parents gave my daughter their 2002 Chevy Trailblazer about a year ago. My dad gets the oil changed, but nothing else. It had just over 150K miles on it. I ended up dropping the AT pan, replacing the filter, and then replacing the fluid that came out with Supertech Dex VI. 6 months later I used my fluid extractor, and swapped out about 3 more quarts and replaced with ST Dex VI again. I'll probably do the same thing again later this summer.

I don't know if I've extended the life of the transmission by doing all of this, but it shifts well and I certainly haven't caused anything to blow up. It has been about a year. YMMV.

 

[burchster13]

I worked at a quick lube in college. We did our trans services via the cooler line no machine. We did very few of them. People do not take care of there transmissions fluid wise it's very frustrating when used car shopping.

 

[UnclePeco]

Originally Posted By: JimPghPA
Originally Posted By: slacktide_bitog
What car?


And what is the terrain like?

I would like to see someone get that kind of life, without a fluid change, driving the hills of Pittsburgh or some place similar.


Agreed - the mountains, dirt roads and winters in northeast, pa would kill that trans much sooner

 

[BowNisPar]

Why not just do a pan drop with fluid and filter change? Nearly impossible to hurt anything, plus you'll get XX% of the old stuff out, and get a nice view of the fluid and filter condition. Short of you breaking something, it can only help.