Transmission Service Discussion

[HARDTRAILZ]

I fully expect near 250,000 out of this one.

My lifted 88 s10 blazer made 260,000 on one motor

My lifted 91 Burban has 245000 on motor, the rest I have upgraded.

My lifted 94 blazer had 165 when I sold it

The lifted ext cab s10 had 150 on the 2.8 when I replaced it and got good cash for it a few months later.

I had 3 f-bodies with oer 120,000. 2 lt1 and 3.8.

My bro has 220K ok a 98 blazer, his 96 had over 200 when it got hit from behind and bent the frame where the back doors wouldnt seal and I drove it for a half a winter like that while we fought the ins co.

My dads 2000 z71 has 235k and he put a tranny in at 180 cause he said it ran strong enough it would wear out another tranny.

My sis lil sunfire ws just sold for 1000 with 289,211 miles last week.

GM will last if you just do regular maintenance. We alsways use convetional oil every 3-5k miles. Never open a gm tranny unless you want it to fail. We had 2 serviced and they both only lasted a few months after. Run some fuel cleaner from time to time and air filter every other oil change.

My dad and i are both in real estate and drive a ton and we both swear by Chevy.

[Trail X]

You never service your transmissions? Not even change the fluid or filter?

[HARDTRAILZ]

Nope. Check fluid and add if needed occasionally, but everytime we have had one serviced, it fails within a couple months. I have been reading lately about doing it and they are saying this could be due to changing filter and fluid at same time and crud breaking loose and screwing things up. I debated about just changing fluid, but hate to ruin it.

If it aint broke...dont fix it.

[Trail X]

So why do you change your engine oil? If it's not broke, don't replace the oil.

[irishboy02]

With transmissions, its not always good to do a full change flush, esp autos. Over time, the clutches wear out, causing the particles to breakdown inside the fluid. If theyre in the fluid which its being used, its act the same way, but if you changed the fluid it remove these particles, the trans will actualy seize or start slipping...

add dont replace

[Trail X]

My understanding is that it's all about WHEN you change it. If you change it after 100k you're opening yourself up for slippage, under 100k you're most likely ok.

The other concern when changing fluid is that you never want to drain the torque converter, it can develop air pockets which will destroy the TC.

[HARDTRAILZ]

Yep if you do them at regular intervals from new, then it seems to work. If the tranny starts acting up, then I will usually do it to get a couple more months from it, but unless it was done from new I dont screw with it.

I change the TC fluid, diffs, and oil, because I have not had that cause failure after doing them.

I dont screw with transmissions due to experiencing multiple failures after servicing. If i stating having motors fail after changing oil, I will quit changing it as well.

I have never heard of the air pockets in the convertor.

[bartonmd]

Oh boy, here we go...

It's got nothing to do with clutch wear, or clutches being "used to" old fluid... especially on computer controlled transmissions that adjust pressures based to shift time, go get the correct shift time (per calibration)... If you get slippage when you change the fluid, you had a problem to begin with...

You've got to drop the trans to empty the torque converter... If you do this, you want to fill it up as much as you can before re-installing it on the input shaft... If it's got any real amount of fluid in it, it's fine...

The reason transmissions sometimes fail after you get a lot of miles on them, then change fluid, is usually because the filter plugs up and starves the thing for fluid... Old trans fluid has lost (or used up) its additives, and stops fighting buildup inside the transmission... When you replace that fluid well after the buildup has gotten away from you, you introduce all new additives, which break up the buildup, and send it through the system... Sometimes, you'll get it stuck somewhere important, and will starve something for fluid and kill it... Most of the time, though, all the buildup makes its way through the system, and plugs the filter, which starves the whole system for oil... The way to do it is; flush the system, then a couple weeks of driving later, do the filter... You've probably caught the old filter before it's plugged, and you won't completely plug your new filter from the get-go...

FWIW, knock on wood, I drive old iron, and I've done a trans service on everything I've ever had (some of which had well over 100k without fluid changes, including my S-10 Blazer that had towed a 5k# boat for the first part of its life, and had 160k miles with no trans service, ever. Trans fluid literally looked like used motor oil, and smelled HORRIBLE)... I've not lost a trans on anything that I've owned, that wasn't a "hard part" failure (input sprag)... But then, I always change the filter...

Mike

[janesy86]

When I changed my trans fluid a couple weeks ago, all I did was drop the pan, change the filter and filled it back up with about 7qts or so of new fluid. I'd say it feels a lil bit better and glad I did it and will do it again at 100k or so...

[HARDTRAILZ]

I used to tow up to 8000 lbs all the time. we got a bobcat and a 4wd tractor that went behind the s-blazers and the z71. good trailer brakes were a ust, but handled it ok.

[HARDTRAILZ]

... If you get slippage when you change the fluid, you had a problem to begin with...
which is usually when people service a tranny

The reason transmissions sometimes fail after you get a lot of miles on them, then change fluid, is usually because the filter plugs up and starves the thing for fluid... Old trans fluid has lost (or used up) its additives, and stops fighting buildup inside the transmission... When you replace that fluid well after the buildup has gotten away from you, you introduce all new additives, which break up the buildup, and send it through the system... Sometimes, you'll get it stuck somewhere important, and will starve something for fluid and kill it... Most of the time, though, all the buildup makes its way through the system, and plugs the filter, which starves the whole system for oil... The way to do it is; flush the system, then a couple weeks of driving later, do the filter... You've probably caught the old filter before it's plugged, and you won't completely plug your new filter from the get-go...

So you are saying...Drain fluid, refill and drive a few weeks, drop pan and change filter, fill appropriately and it will work without destroying a tranny?

[bartonmd]

I used to tow up to 8000 lbs all the time. we got a bobcat and a 4wd tractor that went behind the s-blazers and the z71. good trailer brakes were a ust, but handled it ok.

This was a 2-door 4.3, and Im sure it handled it OK, but the fluid was BURNT... They lived in Bloomington, and towed it too and from Lake Monroe every weekend... (read: hills)

Mike

[bartonmd]

... If you get slippage when you change the fluid, you had a problem to begin with...
which is usually when people service a tranny

The reason transmissions sometimes fail after you get a lot of miles on them, then change fluid, is usually because the filter plugs up and starves the thing for fluid... Old trans fluid has lost (or used up) its additives, and stops fighting buildup inside the transmission... When you replace that fluid well after the buildup has gotten away from you, you introduce all new additives, which break up the buildup, and send it through the system... Sometimes, you'll get it stuck somewhere important, and will starve something for fluid and kill it... Most of the time, though, all the buildup makes its way through the system, and plugs the filter, which starves the whole system for oil... The way to do it is; flush the system, then a couple weeks of driving later, do the filter... You've probably caught the old filter before it's plugged, and you won't completely plug your new filter from the get-go...

So you are saying...Drain fluid, refill and drive a few weeks, drop pan and change filter, fill appropriately and it will work without destroying a tranny?

Exactly... A lot of times, a trans starts acting funny, so people change the fluid to "fix it", and blame the fluid change when the trans goes a few weeks later (not you, but a lot of these cases)

Yours came with Dex 6 from the factory, I think... A pan drop, filter, and replace fluid, and you should be good to go... ETA: Especially since I know a lot of yours is highway mileage, and you don't tow heavy every day, and the additives also go with time... you've got a lot of miles, but not very much time... I changed the filter on, and refilled, plus flushed about 3 extra quarts on my '93 LeSabre with 120k on it (fluid never changed)... It's been a year, and it's still great...

But yes, flush, drive a couple weeks, then change filter and top off...

Mike

[HARDTRAILZ]

Exactly... A lot of times, a trans starts acting funny, so people change the fluid to "fix it", and blame the fluid change when the trans goes a few weeks later (not you, but a lot of these cases)

Yours came with Dex 6 from the factory, I think... A pan drop, filter, and replace fluid, and you should be good to go...

But yes, flush, drive a couple weeks, then change filter and top off...

Mike

I keep wavering on doing it since it does have miles, but as far as I can tell the ones before me were fairly easy ones. Also the newer fluids are a little better than the early 90's or previous junk.

But reading above...are you saying if I do it to change it all at once and call it good or do the drive a couple weeks between?

[bartonmd]

Exactly... A lot of times, a trans starts acting funny, so people change the fluid to "fix it", and blame the fluid change when the trans goes a few weeks later (not you, but a lot of these cases)

Yours came with Dex 6 from the factory, I think... A pan drop, filter, and replace fluid, and you should be good to go...

But yes, flush, drive a couple weeks, then change filter and top off...

Mike

I keep wavering on doing it since it does have miles, but as far as I can tell the ones before me were fairly easy ones. Also the newer fluids are a little better than the early 90's or previous junk.

But reading above...are you saying if I do it to change it all at once and call it good or do the drive a couple weeks between?

If you're going to do a "flush" and change it all, wait a couple weeks and do the filter... If you're just going to do the filter + refill, just once is fine...

Does the fluid look trashed, or does it look OK?

Mike

[HARDTRAILZ]

Honestly it has been about a month. It is not horrible. i have seen better and I have seen worse. I just am thinking with this past weekends trip to the Quad City meet of 600plus miles and Tecore and Carlisle this summer with up and down and twisties, it might be a smart thing to do if done right. That is why I had been researching it and saw about the same as you stated and I mentioned about doing it in "stages". I dont have any issues, so it is probably safe to do, but I will rcheck the fluid and probably at least change the filter and refill.

[bartonmd]

Honestly it has been about a month. It is not horrible. i have seen better and I have seen worse. I just am thinking with this past weekends trip to the Quad City meet of 600plus miles and Tecore and Carlisle this summer with up and down and twisties, it might be a smart thing to do if done right. That is why I had been researching it and saw about the same as you stated and I mentioned about doing it in "stages". I dont have any issues, so it is probably safe to do, but I will rcheck the fluid and probably at least change the filter and refill.

Changing the filter and re-filling is about the safest thing do to...

Mike

[Trail X]

I have heard though... do not have one of the "forced" flushes done on your trans.

There's two ways to do it, I don't know all the ins-and-outs of it, but one forces fluid through the trans, and one uses the trans pump to flush the fluid,... don't use the forced method.

I took the input and output lines off the trans cooler and ran the trans output into an empty container and put the intake line into a tub of new Dex 3... I ran 8 quarts of Dex 3 through the transmission this way... the output fluid looked really clean by that time. It's my understanding that this helps clean out the torque converter from old fluid. Then I dropped the trans pan, changed the filter, and refilled with Dex 6. This method apparently changes the converter fluid while never unfilling it...

It's worked fine for me so far, but I only changed it back in Jan. Similar method to what Mike suggested, just didn't run it as long with the temporary fluid.

[HARDTRAILZ]

If I am gonna do it...what are some thoughts on a plus 2 qt pan or finned pan or getting one with a drain plug?

Any certain fluid or filter to buy or to avoid?

JD--Why not split this discussion off and put it somewhere so it can be found easily for people in the future?

[bartonmd]

If I am gonna do it...what are some thoughts on a plus 2 qt pan or finned pan or getting one with a drain plug?

Any certain fluid or filter to buy or to avoid?

JD--Why not split this discussion off and put it somewhere so it can be found easily for people in the future?

My only thoughts are:

- Get a +2qt pan
- Get a pan with a drain plug
- Deeper pans come with filters, don't they? If not, I try and get AC Delco, but I don't know that it matters...
- Anything that says "Dex 6" (which is the only thing that should go in your trans) is all the same stuff... I used the Super Tech stuff on the TB, and it's been doing fine...

Mike