Transmission life on the early Hoes?

[nonickatall]

I was a GM dealer tech, started at Chevy dealer in mid-70's. Never worked at a shop that had a transmission flush machine and have never done a transmission flush. I've done countless transmission services on newer vehicles and high mileage vehicles, basically drop pan, drain fluid, replace filter and fluid. I've never had one that went bad because of "stirring something up". Those that went bad were on their way well before the service and they were trying to band aid it. Anything that might get "stirred up" would be stopped by the filter. I think some of the tales might have been started back in the old filter style days where the filter might have been prone to clogging, I'm talking real old days.

I also think that gearboxes, that fail after an oil change, are gearboxes where the oil change was made, because the gearbox ran poorly and one hoped that the oil change would improve the situation.

Transmission flush maschines as they are necessary in Germany are probably popular for two reasons, firstly, with today's transmissions it is no longer the case that you simply change the oil with the oil dipstick to check the oil level and everything is fine.

If you change the oil in an modern Audi, for example Then you have to use a pump to push the transmission oil into the transmission pan from below. This has to happen at a very specific transmission temperature.

You then have to bring the transmission to a very specific temperature which you need to read out in your software system where you have access to the transmission and then you must set the transmission oil to the right level. The German car manufacturers manage it to change a transmission from something completely banal to rocket technology close.

But changing the way it used to be done by you, by removing the pan, changing the filter and refilling the oil that came out of the gearbox, doesn't help much from my point of view, because if I overhaul a gearbox and the gearbox is completely dry, then I fill about 9 liters of oil into the ystem. When unscrewing the oil pan, only about 3.5 liters of oil come out.
And that is in almost all of the transmissions, because 2/3 of the oil is in the transmission and does not come out of the pan during a normal oil change.

And If you look at the filter of an automatic transmission, you will see that it is not a paper filter like oil filters or another material that filters out the finest particles, but it is usually a fiber filter in a tin can or plastic housing.

This service to catch chunks that have broken off somewhere. Point of abrasion in a gearbox is so fine that it doesn't matter much to the gearbox. And the other metall wear is catchet by the magnets in the oil pan.

That's why I still think that: If I had the choice of removing the oil pan and changing the filter and swapping only 1/3 of the oil.

Or leaving the filter where it is and flushing the transmission through the oil cooler, I would always prefer that method, because you can change almost 100% of the oil.

The very best method you can do to your transmission is of course, removing the pan, replacing the filter and possibly replacing the shift magnets as with the GM transmission, then mount the pan back on and then flushing the transmission to remove the remaining 2/3 of the old oil from the transmission. But since this is a considerable effort for most hobby DIY.

I would rather just flush the gearbox, which every layman can do and thus do 90% maintenance instead of do nothing because being afraid to do the rest 10% as well.

 

[Mean_Green]

I'm asking this because I bought this more or less blind and in hopes it would last me until I don't need a vehicle any more. I have a 95 Taurus GL wagon that has been mostly dependable, but has left me stranded a few times. So far no really major money, but a lot of aggravation. It's at 135K and the point of needing some of what's in the above post. I have a shade tree guy who can do some of that, but he's a one man shop and doesn't do warranties. I need to get that one scheduled for a fluid and filter change.

I'm hoping I didn't buy into a world of trouble with this beast. My funds are far from unlimited as some of yours seem to be with all the high end custom mods I see. I just want it to run when I need it to and do a bit of towing about 2,500 pounds once in a while.

I wanted something bigger than the station wagon, but not really a truck truck.


Reading through some of these other threads, it seems some people think the 90s versions were more reliable and durable than the 00s and up. I hate how vehicles have become rolling computerized entertainment centers and nanny bots and wanted something made before all that took hold.

.

 

[Eman85]

135k is like a low mileage vehicle in todays world. There's plenty that can go wrong but on a vehicle like yours it's fixable and affordable. There are common problems and they are well documented on this board and you will experience some of them. As far as Transmisson goes the one aggravating fault is the TCC valve wears in the bore and will set a code P1870. There are fixes for it and they aren't expensive, it's just something to deal with. Changing fluid and filter does help keep the TCC in good shape and the new lubrication helps slow the valve wearing the bore.
I've got a few of this generation trucks as they were my favorites when they were new. I'm old and so are my vehicles. I really don't get excited about newer vehicles and they can be a pain to work on.

 

[willxfs]

I have a 1998 2 door tahoe, 4wd. It had 225k miles on the original transmission when the worn TCC valve started causing harsh 1-2 shifts and the accompanying P1870 code. I had the transmission rebuilt at that time. This was back in 2012. I still have the truck but it is not my daily driver anymore. I've put another 60k miles on the truck since then. Been good so far. Now I wish I would have tried the TCC fix just to see how many more miles the transmission would have ran. I figure I cant complain about 225K miles on the original transmission. It was well cared for and not driven too hard...

 

[Mean_Green]

^^^ I put about 3-4,000 miles on both cars total per year. It's taken about 20 years to put 50,000 on my Taurus. At 195K, to add another 20 - 30,000 could be 10 years or more. And it will be a very easy 10 years. Maybe some light towing at most. Trips generally under 100 miles each, once or twice a month.

 

[sdsuburb06]

I've got 97 k1500 with 245k miles that I purchased from the original owner with 85k miles. He provided no service records, but a sticker under the hood indicated a BG transmission service was done at 75k miles, and I had the fluid exchanged at 172k miles. Truck spends most of its time towing a boat in 3rd gear in some hilly terrain and its never shown any signs of transmission issues. Fluid always looks good upon checks, it shifts smooth and it's all original hardware.

 

[the 18th letter]

I was a GM dealer tech, started at Chevy dealer in mid-70's. Never worked at a shop that had a transmission flush machine and have never done a transmission flush. I've done countless transmission services on newer vehicles and high mileage vehicles, basically drop pan, drain fluid, replace filter and fluid. I've never had one that went bad because of "stirring something up". Those that went bad were on their way well before the service and they were trying to band aid it. Anything that might get "stirred up" would be stopped by the filter. I think some of the tales might have been started back in the old filter style days where the filter might have been prone to clogging, I'm talking real old days.

I went to a GM dealer recently for my manual scheduled 100k transmission fluid change and the dealer refused stating the fluid wasnt clear, ( d'uh) and they had too many problems when changing dirty fluid. Made absolutely no sense to me.

 

[strutaeng]

I went to a GM dealer recently for my manual scheduled 100k transmission fluid change and the dealer refused stating the fluid wasnt clear, ( d'uh) and they had too many problems when changing dirty fluid. Made absolutely no sense to me.

Old wives' tales is "don't replace old transmission fluid because the 'grit' floating around helps keep the clutches from slipping."

It's the dumbest idea floating around that even a lot auto mechanics and shops believe to be the Gospel!

My 99 Silverado had like 230k and I took it for a fluid change at the local Pennzoil shop. They made me sign a waiver due to the high mileage, probably for the same idea. I didn't know how to do a basic ATF change back then. By then my transmission already had the P1870 and I ran it until 260k for another 3-4 years. Fluid still looked clean when I pulled it and still shifted good except for the valve body code. I've always try to replace fluid between 50k-75k on the 4Lxx transmissions after the 100k Owner manual recommended mark.

 

[Eman85]

I went to a GM dealer recently for my manual scheduled 100k transmission fluid change and the dealer refused stating the fluid wasnt clear, ( d'uh) and they had too many problems when changing dirty fluid. Made absolutely no sense to me.

They probably have been down that road with previous customers. Someone comes in with a high mileage vehicle, has the fluid changed and then a month later the trans goes bad. Of course, it has to be the shops' fault that changed the fluid and with enough threats a trans rebuild is cheaper than a lawsuit so then they stop doing fluid changes on high mileage vehicles.

 

[the 18th letter]

They probably have been down that road with previous customers. Someone comes in with a high mileage vehicle, has the fluid changed and then a month later the trans goes bad. Of course, it has to be the shops' fault that changed the fluid and with enough threats a trans rebuild is cheaper than a lawsuit so then they stop doing fluid changes on high mileage vehicles.

That's possible but also suggests that GM should update the owners manual to require it before 100k.