2000 Tahoe Transmission fluid - Should I change it?

This truck has been in the family since it was new so I know it's history and now has 140,000 miles. I don't drive it as much lately and 40,000 of those miles occurred in the past 8 years. Anyways, I did bring it in for a 100,000 tune up back in 2009 and they said the transmission fluid looked fine and didn't recommend changing it. It still has never been changed and I have read several posts in different areas that say if you haven't changed it by 100k, don't change it as it could cause problems by dislodging metal shavings or something. What do you think? What signs should I look for if anything is wrong? The fluid still looks clean as far as I can tell (would it be more brown if it were dirty? Still looks red to me). Any advice on this will be helpful. I still don't use it that often, but will be doing several camping trips this summer pulling a light 2,000 lb trailer.

Ok, I think I was mistaken. I must have confused that with a transmission flush. Apparently just changing the fluid won't hurt, is that correct?

dman76 said:

Ok, I think I was mistaken. I must have confused that with a transmission flush. Apparently just changing the fluid won't hurt, is that correct?

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There is a bit of contention on this. First off, the trans dipstick is deceiving. It can look clean when it's really not. Does it smell burnt at all? Unfortunately there is not a drain plug on the stock pan, so you have to drop it to change fluid unless..... You use the radiator trans cooler line to pump it out. Imo, this is a pretty genius move. You can "flush" as little or as much fluid as you like. You can just pump out the 5 qts in the pan if you are worried about it. If you can't find the procedure, lemme know and I'll find the link. There is a great write up over on GMFS.

If I do that method, I can't change the filter. I imagine that should be changed since it never has been. Is dropping the pan that difficult? Do you really have to remove the exhaust bolts?

buy 5 or 6 quarts of Dexron 3 a good Filter AC Delco or WIX... and change the oil.
1 hour work in front of your garage... Your Truck will love it !

And you feel better too - because you know that everything is o.k

Greetings Juergen

p.S I know that nowadays there is Dexron 6 Transmissonfluid on the market...but I would stick with the proper Dexron 3 because mixing oils is´nt a good idea.

dman76 said:

If I do that method, I can't change the filter. I imagine that should be changed since it never has been. Is dropping the pan that difficult? Do you really have to remove the exhaust bolts?

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Most guys say you can "bend" things to squeeze that baby outta there. The shifter cable bracket and the y pipe. BTW, if you combine the two methods, you can drop the mostly empty pan to change filter and gasket instead of spilling 5 qts of fluid all over the place...

HiHoeSilver said:

BTW, if you combine the two methods, you can drop the mostly empty pan to change filter and gasket instead of spilling 5 qts of fluid all over the place...

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This is the method that I am planning to use when I tackle this project later this summer:

1. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
2. Drop the near empty pan and swap out the filter
3. Reinstall the pan with a new gasket
4. Refill the pan with transmission fluid to the cold line on the dipstick (~4qts)
5. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
6. Refill the pan with transmission fluid to the cold line on the dipstick (~4qts) (Total of ~8 new qts)
7. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
8. Refill the pan with transmission fluid to the cold line on the dipstick (~4qts) (Total of ~12 new qts)
9. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
10. Refill the pan with transmission fluid to the cold line on the dipstick (Total of ~16 new qts)
11. Reconnect the trans cooler line
12. Drive the vehicle and adjust the final level of the ATF to the hatched area

I've seen a few write ups that do the full flush with new fluid and the old filter, then pump the pan dry one more time to install a fresh filter at the end. They then add 4 more qts of new. This of course use additional fluid, about 20 qts in all, but the new filter has no chance of becoming contaminated from the old ATF. I think that is a little overkill, since the filter should always be drawing from the sump that has just been filled with fresh fluid.

Like I've said, I haven't done this yet. This is the method that I have pieced together from various sources, and that I am comfortable tackling.

mals said:

This is the method that I am planning to use when I tackle this project later this summer:

1. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
2. Drop the near empty pan and swap out the filter
3. Reinstall the pan with a new gasket
4. Refill the pan with transmission fluid to the cold line on the dipstick (~4qts)
5. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
6. Refill the pan with transmission fluid to the cold line on the dipstick (~4qts) (Total of ~8 new qts)
7. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
8. Refill the pan with transmission fluid to the cold line on the dipstick (~4qts) (Total of ~12 new qts)
9. Use the cooler line discharge at the radiator to pump out the ~4 qts in the transmission pan
10. Refill the pan with transmission fluid to the cold line on the dipstick (Total of ~16 new qts)
11. Reconnect the trans cooler line
12. Drive the vehicle and adjust the final level of the ATF to the hatched area

I've seen a few write ups that do the full flush with new fluid and the old filter, then pump the pan dry one more time to install a fresh filter at the end. They then add 4 more qts of new. This of course use additional fluid, about 20 qts in all, but the new filter has no chance of becoming contaminated from the old ATF. I think that is a little overkill, since the filter should always be drawing from the sump that has just been filled with fresh fluid.

Like I've said, I haven't done this yet. This is the method that I have pieced together from various sources, and that I am comfortable tackling.

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Pretty much my plan, too. Maybe a new pan with a drain plug in case I ever want to freshen up. Did you decide on fluid?

The first time i did mine at 100k i dropped the pan, changed filter, and refilled with dex-3 and then did the pump out and refill method like above. Works great. At 150k I got crazy and did the same pumping out method with dex-6, an ac filter/gasket, and new cooler lines cuz they were leaking. I didn't see any difference in how it behaved after but its good piece of mind. I'd say as long as you steer clear of a FLUSH you should be good. I slightly bent the shift cable bracket to get to the bolts behind it on the pan, never got close to the y pipe being as issue.

HiHoeSilver said:

Pretty much my plan, too. Maybe a new pan with a drain plug in case I ever want to freshen up. Did you decide on fluid?

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Same here. I may do a pan like the PML aluminum one with the cooling fins since I tow a lot. I will be going with the Amsoil ATF that is Dex VI compatible.

UPS just dropped offer a package of Amsoil Severe Gear 75w-90 for my differentials and ATF Dex III for my transfer case today. If all goes well they will be in my Yukon by the end of the week.