Trans Fluid Change Myth/No Myth???

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RichardSenn

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Okay, so unfortunately I was raised believing the Transmission fluid change myth that if you haven't changed the fluid and you're past 100K then you are better off not changing it. I know I know you don't even have to say it, should have changed it earlier.
frown.gif


I'm new to the forum and have already learned a wealth of knowledge but I'm so torn up about this and I've read so many transmission threads my head is spinning. My truck has 135K on the original transmission fluid. It's been topped off before but never changed. So now I'm torn on what do.

It's a 460LE and shifts fine and shows no indications of failing but changing the fluid now really scares me. Also, the transmission fluid is still bright red and has a sweet smell. So because I've already read the threads with half the people saying change it and half saying don't change it so I have another question.

How many of you have changed your transmission fluid for the first time at or after 100K and what were your results? Please specify if you dropped the pan to change the filter or if you flushed it without changing the filter.

I realize most of you are on top of your fluid changes so I may have no responses for people doing there first change after 100K. If only I had joined this forum 5 yrs. ago, but I was a little younger and thought I new it all.
 
Changed it on our Vibe for the first time at 86k. Let it go too long. Just caught up to me, I guess, in the one year that my wife put 45k miles on it. I got a full flush at the dealer. Transmission shifted fine, just thought it was time. No problems whatsoever. I did a drain and fill on my own at 106k, including adding a bottle of Lubegard red bottle. I plan to get a full exchange again at the dealer at 145k or so next spring.

Change your fluid.
 
I'm a mechanic, and I have seen a couple transmissions that never moved again after the fluid was changed, and this is the basis for the horror stories you are hearing. However, these instances are few and far between and virtually never happen with a transmission that wasn't acting up in some way before hand. However I must warn... DO NOT UNDER ANY CIRCUMSTANCES, EVER HAVE IT FLUSHED!!! The transmission shop we use to rebuild the few we have done says he LOVES transmission flushes, cause after people have them flushed, they bring them to him to have them rebuilt!!!
 
Did a full fluid replace on my Lexus GS transmission at 85k. Worked great. No trouble to report. One would assume the transmission failure would only occur if the transmission had lots of built up. Maybe a Magnefine filter with the fluid change?
 
I just changed out most of the fluid in my 2006 Honda Odyssey 100k miles. The van is new to me but I have complete service records from the previous owner and it had never had any transmission service.

I drained 3.5 quarts and then started the engine shifting through each gear for ten seconds until I got about four quarts of old fluid out of the coolant line. I never saw new fluid come out of the line. I left it at that because I was under a time crunch to get the van ready for vacation. The old fluid was tinged blue gray from what I assume was wear or aluminum sloughing off the case. Installed a Honda transmission cooler from a 2007 model, put in a magnafine filter and filled with new Honda DW-1.

Towed a 2000 lb pop-up camper 2800 miles across the mountains of Idaho, Wyoming, Utah and Colorado without issue.

I wish I could say it was shifting at all different after all the work but it's not. The old fluid looked spent but was apparently running fine.

If your fluid looks good then I say change away. It can only help. If the fluid was burnt and had been for a long time to the point where only the varnish was keeping the internals together then I can see a change causing issues but I'd still change it.
 
I would just do it gently and not worry much. Best bet is to get yourself some kind of suction device. Remove 1-2 quarts or whatever you can get out of the dipstick hole, fill with fresh fluid, drive a week or two, repeat.

After having replentished the fluid and let it do its work to clean/solve anything that it might, then do a pan drop and replace the filter and the lost fluid. Drain the TC if you can.

Repeat after a few thousand miles and then you should be good.

Doing it this way will let any cleaning get done slowly, and doing multiple filter changes means that any junk that may be present will be removed, so you should retain good flow/pressure.

This technique has worked great for me a few times.
 
Change the fluid/filter and there's a small chance you'll do more harm than good. If you do nothing, you will be buying a new transmission at some point.....

Change it if you ask me.....
 
Drop the pan and change the filter and the fluid. Won't hurt and might help.

The original gasket can be re-used if it's in good condition.

GM transmissions have a real filter in there. Not just a screen.
 
Originally Posted By: JHZR2
I would just do it gently and not worry much. Best bet is to get yourself some kind of suction device. Remove 1-2 quarts or whatever you can get out of the dipstick hole, fill with fresh fluid, drive a week or two, repeat.

After having replentished the fluid and let it do its work to clean/solve anything that it might, then do a pan drop and replace the filter and the lost fluid. Drain the TC if you can.

Repeat after a few thousand miles and then you should be good.

Doing it this way will let any cleaning get done slowly, and doing multiple filter changes means that any junk that may be present will be removed, so you should retain good flow/pressure.

This technique has worked great for me a few times.


I did somewhat different for my '00 E430 at 80+k miles 3-4 years ago. First I had the car at my local shop, the mechanic drop the pan and replace the filter, he measure the ATF fluid came out of the pan and replaced with OEM fluid, there is no drain plug to drain from TC. After driving for a week I used Mityvac to siphon about 3-3.5 quarts from the dipstick tube and replaced the same amount with OEM fluid, I repeated that 2 more times. I used a total 14 quarts while the capacity is 8.5 quarts. I will siphon 2-3 times again when the odometer shows 140-150k miles.

I think your way may be better for older transmission with more than 100k miles that has FF fluid.
 
I just did a cooler line flush on a friend's '98 V70, 135K miles, original fluid. It was actually shifting fine, and the 4 speed box in that car is notoriously robust.

The fluid looked good on the dipstick. It looked really rough though after we drained it (not sure why such a difference). He has about 5K on it since, and the only difference is that it's shifting a little more smoothly...

If you're really paranoid and it's not a hassle on your car, you could do a couple drain and fills first, then a full flush. I thought about it, then thought about the logic behind it, and decided it was a waste of time. So, that's my real-world example of doing this on a high mileage vehicle with the OEM fluid still in place.
 
Originally Posted By: JHZR2
I would just do it gently and not worry much. Best bet is to get yourself some kind of suction device. Remove 1-2 quarts or whatever you can get out of the dipstick hole, fill with fresh fluid, drive a week or two, repeat.

After having replentished the fluid and let it do its work to clean/solve anything that it might, then do a pan drop and replace the filter and the lost fluid. Drain the TC if you can.

Repeat after a few thousand miles and then you should be good.

Doing it this way will let any cleaning get done slowly, and doing multiple filter changes means that any junk that may be present will be removed, so you should retain good flow/pressure.

This technique has worked great for me a few times.



This is what I would recommend as well if you are worried about issues.

In my experience changing the fluid is better than not changing it the vast majority of the time. The only time I wouldn't change it is if the transmission is starting to slip. Changing the fluid will cause it to slip more and possibly be un-driveable.

Past a certain mileage? That doesn't make sense on any planet. 100k miles on the freeway is going to put the same amount of wear on the fluid and less wear on the plates than 25k around town.
 
I have yet to find ANY shop with any kind of "flushing" machine. All anyone uses is a simple two tank cabinet that uses your own trans pump to move the fluid. If used correctly it is virtually impossible to muck up anything, and even pumping it out into a bucket and refilling is very gentle and easy. The only place people mess up is they don't change the filter/screen.

The tales of woe heard about old trans are just that, tales. I have bought many many vehicles with way more than 100k miles, exchanged with all new fluid and filter, and actually SOLVED issues many times. This includes imports and domestics.

Note that your trans is actually a 4L60-E, and needs regular service to last a long time. If ignored it may fail kind of early. The later model 4L65-E is much more durable.
 
A few years ago I used to buy "beater" cars for a few thousand dollars to drive when I had my mustang. I had a 1994 MGM with 110k on it that never had the fluid changed. I did a pan drop on it and put in maxlife fluid. Ran great for another 50k before I got rid of it. I then picked up a 1992 buick regal with 94k and I assume it never had a fluid change before me. But it also ran grat for another 30k before I got rid of it. NO FLUSHING!!!!
 
Originally Posted By: RichardSenn
It's been topped off before but never changed. So now I'm torn on what do.


What does this mean? Is it leaking?
 
I had the pan dropped and filter replaced on my Explorer at around 65k. However, I then went an additional 90k or so before changing it again: I had the transmission flushed at around 135k. I decided I should probably change the filter again so I dropped the pan again at around 145k. The trans still shifts prefectly at 162k.
 
Some shops will not change fluid on higher mileage vehicles with poor service records, because if anything does fail it gets blamed on the shop, even if the reason the AT failed was due to mileage.

New fluid can't hurt an old transmission unless the new fluid is incorrect.
 
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