Thoughts on changing transmission fluid

[tmt502]

So my “new to me” Tahoe has 221k on the clock. I’m calling the last shop of service recorded on Carfax (213k was the last service back in February - shows as oil change and tire rotation) tomorrow with hopes to get some input on the service history of the vehicle. Records show they’ve done all of the regular service since 54k miles back in ‘14. Before that was all at the local dealership it was purchased from new. The only exception being a torque converter replacement at 76k miles, which was done at the dealership.

My intent is determine if the service shop, which is also local, has done any transmission maintenance, ever. A couple of the entries on carfax just show “vehicle serviced” with no detail, whereas all others give some detail of the services performed. None of the service details indicate a trans service.

The question I have is this, should I change the trans fluid and filter if it hasn’t been done since the torque converter replacement at 76k? The dealership confirmed For me today that they did replace the fluid and filter along with that service. I’ve heard/read plenty of anecdotes that you shouldn’t change the fluid if it’s never been serviced or hasn’t been serviced over 150k miles (which I’m coincidentally right on), otherwise this will cause the trans to fail in short order for various reasons. It feels strong and shifts great for what little (150ish miles) I’ve been able to drive it over the last few days I’ve owned it.

If that’s the case, should I just plan on replacing the trans to remedy this? This is a second vehicle I use for work travel (I’m an engineer that visits project sites and clients), but I plan to start towing with it soon too.

I’d appreciate some input. Thanks!

 

[swathdiver]

So my “new to me” Tahoe has 221k on the clock. I’m calling the last shop of service recorded on Carfax (213k was the last service back in February - shows as oil change and tire rotation) tomorrow with hopes to get some input on the service history of the vehicle. Records show they’ve done all of the regular service since 54k miles back in ‘14. Before that was all at the local dealership it was purchased from new. The only exception being a torque converter replacement at 76k miles, which was done at the dealership.

My intent is determine if the service shop, which is also local, has done any transmission maintenance, ever. A couple of the entries on carfax just show “vehicle serviced” with no detail, whereas all others give some detail of the services performed. None of the service details indicate a trans service.

The question I have is this, should I change the trans fluid and filter if it hasn’t been done since the torque converter replacement at 76k? The dealership confirmed For me today that they did replace the fluid and filter along with that service. I’ve heard/read plenty of anecdotes that you shouldn’t change the fluid if it’s never been serviced or hasn’t been serviced over 150k miles (which I’m coincidentally right on), otherwise this will cause the trans to fail in short order for various reasons. It feels strong and shifts great for what little (150ish miles) I’ve been able to drive it over the last few days I’ve owned it.

If that’s the case, should I just plan on replacing the trans to remedy this? This is a second vehicle I use for work travel (I’m an engineer that visits project sites and clients), but I plan to start towing with it soon too.

I’d appreciate some input. Thanks!

These 6-speeds are a different animal, change it.

I called the dealerships that serviced my truck before I bought it. One asked for proof of ownership which I emailed and they sent over all the service records right away. The other dealer emailed them to me on my honor.

 

[CaptainAmerica1]

Do it, if it’s gonna die it’s gonna die... new fluid will only help prolong the life...

 

[ivin74]

I did the first tranny oil change at 170k, no issues what so ever and it's been over a year.

 

[kbuskill]

Have you looked at the transmission fluid on the dipstick? How does it look and smell?

 

[tmt502]

Have you looked at the transmission fluid on the dipstick? How does it look and smell?

I have. It has some brownish tint, but still a little pink on a white paper towel. Faint smell of ATF fluid, but not as strong as new. Not sure if that makes sense...

 

[kbuskill]

I have. It has some brownish tint, but still a little pink on a white paper towel. Faint smell of ATF fluid, but not as strong as new. Not sure if that makes sense...

My guess is that it has been serviced at least once since the torque converter swap... but again, just a guess.

If it's not slipping or giving any indications of problems then I wouldn't be afraid to service it.

I flushed mine using the transmission cooler line method and refilled with full synthetic Dex 6 at 208k miles and haven't had a single issue. That was about 45k miles ago and I have the 4L60E 4 speed transmission.

 

[gooffeyguy]

Hook up a Tech2 and see what % the trans oil life monitor is at. If a dealership did any trans service they should've reset it, much like the engine oil life monitor.

Sent from my SM-G930V using Tapatalk

 

[cfmistry]

Definitely sounds like yours has been changed before. I’d go ahead and replace it, but be mindful that your transmission could be near the end of its life with that mileage.

 

[tmt502]

So I got in touch with the local service shop. They confirmed they don't have records of a transmission service being performed there. I went ahead and asked them to quote me a Jasper transmission and rear main seal replacement. We'll see what they come back with and I'll let y'all know what I decide to do.

Any thoughts on Jasper transmissions?

 

[intheburbs]

For the love of all that's holy, please do not even hint at perpetuating the myth "if it's never been changed, don't change it."

If a transmission fails after a fluid change, it was going to fail anyways. But the upside is that you may have extended the life of your trans.

My 6L90 has 200k miles on it, and still functions perfectly. Trans flushes are the only reason my vehicles visit the dealership. I do it every 30k-50k,depending on the duty cycle/how much I'm towing.

 

[79jasper]

When we had our 11 and the trans was going out, had many trans shops tell me the dexron VI loses its color pretty quick. Said cant go off color anymore to judge health.
True or not, no clue. But 3 or 4 shops said that.

Sent from my SM-N960U using Tapatalk

 

[tmt502]

For the love of all that's holy, please do not even hint at perpetuating the myth "if it's never been changed, don't change it."

If a transmission fails after a fluid change, it was going to fail anyways. But the upside is that you may have extended the life of your trans.

My 6L90 has 200k miles on it, and still functions perfectly. Trans flushes are the only reason my vehicles visit the dealership. I do it every 30k-50k,depending on the duty cycle/how much I'm towing.

thank you for that input. That's exactly why I'm here. I want some salt of the earth, reality based input from people who geek out on these trucks.

I asked the shop for the quote just to get an idea of what that cost would be if something does fail after I change the fluid. Just covering my bases for a worst case scenario I guess. Call it risk management if nothing else.

 

[Fless]

thank you for that input. That's exactly why I'm here. I want some salt of the earth, reality based input from people who geek out on these trucks.

I asked the shop for the quote just to get an idea of what that cost would be if something does fail after I change the fluid. Just covering my bases for a worst case scenario I guess. Call it risk management if nothing else.

Seems like an OK plan, just to know. Change the fluid as @intheburbs said, and move on.

 

[89Suburban]

What if someone like me I got over 320K and have no idea of the service life or if it is even the original, but feels fine? I've owned it going on 3 years, maybe put 32K on it since then. Fluid looks okay to me, red and clean? Scared to death to mess with it an kill it from all the urban myths.

 

[donjetman]

Send a sample to a lab for analysis.
JG Lubricant Services
Oil Analyzers Inc
Blackstone Labs

 

[cfmistry]

What if someone like me I got over 320K and have no idea of the service life or if it is even the original, but feels fine? I've owned it going on 3 years, maybe put 32K on it since then. Fluid looks okay to me, red and clean? Scared to death to mess with it an kill it from all the urban myths.

I'll be very impressed if that's the original trans. Most don't make it past 200-250k.

 

[thompsoj22]

Im guessing you have the 6spd and congrats on the new to you vehicle. Drop the pan and take a look, perform a "biopsy" of your trans health. If there isnt a bunch of debris than than you can relax a bit knowing you have done the right thing and "filter/full flush" of the trans. If there is "excessive" debris such as any metal flake or chunks of anything than throw a filter at it and replace the fluid in the pan only with no flush and start looking for a trans/radiator/cooler. I would also advise pricing a GM authorized reman trans and have it installed by the dealer. See if the price difference is worth the 3yr/36,000 mile warranty that includes repair/towing to any dealership in the US. If you are going to tow/travel this is worth alot of peace of mind.

 

[intheburbs]

What if someone like me I got over 320K and have no idea of the service life or if it is even the original, but feels fine? I've owned it going on 3 years, maybe put 32K on it since then. Fluid looks okay to me, red and clean? Scared to death to mess with it an kill it from all the urban myths.

Red, clean and smelling detergenty is a sign of new/healthy fluid. No way, no how that's the original fluid if you have 320k miles. Previous owner(s) must have serviced it.

I will say that next time you change the fluid, upgrade to Dex6. No downside. It's light-years better than Dex3.

 

[Meccanoble]

The transmission drain/refill process is super safe. Unlike a flush that may remove fluid from the transmission itself, the drain/refill only removing the extra fluid in the pan. Letting good fluid circulate into the tranny is the best thing you can do for the tranny. If it fails after that, it literally is on its last leg and will fail soon anyway. If you were taking fluid directly out tranny that needed the dirt to maintain, thats a different story but drain and refill is only removing the extra.