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2003 chevy trailblazer_lt_ext
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Discussion Starter #1 (Edited)
Just bought this 2003 with 160K miles on it. The only transmission fluid (TF) change information I have on it is the previous owner had it for 20K miles and didn't change it. It's in the shop for tie rod replacement and front axle work. Talked to the shop manager about the TF fluid, and he said "I don't recommend flushing it, it's likely that it will cause problems that will have you changing the transmission in a few months. Just top it up".
I've never heard this before and am wondering what to make of it.
 

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2008 gmc envoy_sle
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Just bought this 2003 with 160K miles on it. The only transmission fluid (TF) change information I have on it is the previous owner had it for 20K miles and didn't change it. It's in the shop for tie rod replacement and front axle work. Talked to the shop manager about the TF fluid, and he said "I don't recommend flushing it, it's likely that it will cause problems that will have you changing the transmission in a few months. Just top it up".
I've never heard this before and am wondering what to make of it.
hi and welcome.

theres different schools of thought on this.

some say its ok, others say its no good.

Ive had my 2008 envoy trans fluid flushed at gm dealer (there recommendation, was no charge to me)
about 7 months ago, at 130k Kilometers. and its been perfect. shifts butter smooth.


your results may vary.

at the very least, drop the pan and change the filter.
 

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2003 chevy trailblazer_ls
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Just bought this 2003 with 160K miles on it. The only transmission fluid (TF) change information I have on it is the previous owner had it for 20K miles and didn't change it. It's in the shop for tie rod replacement and front axle work. Talked to the shop manager about the TF fluid, and he said "I don't recommend flushing it, it's likely that it will cause problems that will have you changing the transmission in a few months. Just top it up".
I've never heard this before and am wondering what to make of it.
Changing the oil in the trans used to cause problems on Fords with high mileage because of the type of seals used in the clutch housings. Today, just about all seals in clutch housing are lip type seals and changing the fluid won't hurt.

However, if you are always having to "top it up" you have a leak and that will burn up the trans.
 

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Changing the oil in the trans used to cause problems on Fords with high mileage because of the type of seals used in the clutch housings. Today, just about all seals in clutch housing are lip type seals and changing the fluid won't hurt.

However, if you are always having to "top it up" you have a leak and that will burn up the trans.
he mentioned "flushing" the trans fluid.

with the flushing machine under pressure

odd that his garage would be against that, maybe they don't have the right machine or there not properly educated on the subject.

with Toyota and Gm, its common procedure.
 

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he mentioned "flushing" the trans fluid.

with the flushing machine under pressure

odd that his garage would be against that, maybe they don't have the right machine or there not properly educated on the subject.

with Toyota and Gm, its common procedure.
My mistake but my post is still correct.

Having used a few flushing machines all they do is drain the old fluid by disconnecting a cooler line from the radiator and letting that fluid feed into the old oil container on the machine. Then at the same time new fluid is introduced to the trans from the other cooler line, mixing old and new fluid. They don't "flush" anything and it's basically the same as dropping your pan and adding about 5 or 6 quarts of new fluid on top of the old, while leaving the dirty filter in place.
 

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Discussion Starter #6
Changing the oil in the trans used to cause problems on Fords with high mileage because of the type of seals used in the clutch housings. Today, just about all seals in clutch housing are lip type seals and changing the fluid won't hurt.

However, if you are always having to "top it up" you have a leak and that will burn up the trans.
Thanks. Being that I just got it and the previous owner didn't observe anything, I'll just have to keep an eye on it. Is there any baseline for acceptable rates of loss/consumption? Or is this a no acceptable loss/mile situation?
 

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Thanks. Being that I just got it and the previous owner didn't observe anything, I'll just have to keep an eye on it. Is there any baseline for acceptable rates of loss/consumption? Or is this a no acceptable loss/mile situation?
It def should not leak. no acceptable loss or consumption rate.


you need to inspect all lines and the pan for seepage.

whats the condition of the fluid, is it red, burnt smell ??
 

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Thanks. Being that I just got it and the previous owner didn't observe anything, I'll just have to keep an eye on it. Is there any baseline for acceptable rates of loss/consumption? Or is this a no acceptable loss/mile situation?
I've always held the opinion that any leaking if not repaired will do damage, so I'd say none is acceptable. Also, the trans will not consume oil, just leak.
 

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2006 gmc envoy_denali
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I’d be sure the TF IS TYPE Vl, which is required and check the pan gasket for leaks always . I have a 2096 5.3v Denali and the gasket failed after 100k and required three attempts to stop the leak. Not sure if it’s a poorly designed gasket (Autozone) or what, but they have made nothing on this job. Silicone gaskets don’t seem to be readily available.
 

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Just bought this 2003 with 160K miles on it. The only transmission fluid (TF) change information I have on it is the previous owner had it for 20K miles and didn't change it. It's in the shop for tie rod replacement and front axle work. Talked to the shop manager about the TF fluid, and he said "I don't recommend flushing it, it's likely that it will cause problems that will have you changing the transmission in a few months. Just top it up".
I've never heard this before and am wondering what to make of it.
I had a TF leak on my Trailblazer. There are a couple of mentions of leaking pans here but mine was leaking from a cooling line, from a corroded spot near a support bracket, the stream was too fine to see- I could only see where it was collecting- which just happened to be on the power steering line.. so it took me a while to figure that out!:crazy:

replacing the cooling line is tricky so I clamped some high pressure hose on the leak which worked fine.
 

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I have a 2096 5.3v Denali
I had to check your username to see if it was 'Time Traveler' or something like that... Too bad we are still suffering from the same issues that far into the future, but I guess it's been said for good reason, "Forewarned is forearmed." Thanks for the heads up!

(Just kidding! It just struck my funny bone!)
 

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I had a TF leak on my Trailblazer. There are a couple of mentions of leaking pans here but mine was leaking from a cooling line, from a corroded spot near a support bracket, the stream was too fine to see- I could only see where it was collecting- which just happened to be on the power steering line.. so it took me a while to figure that out!:)

replacing the cooling line is tricky so I clamped some high pressure hose on the leak which worked fine.
Mine does the same, leaks from a trans oil cooler line... I couldn't tell where it was coming from because it was such a fine spray. I'm still not sure if mine is coming from the corroded pipe or the connector that is not replaceable.

I've tried quite a few 'tricks' to make it work, but since the last one failed, I've decided to cut it and put in the transmission hose.
Although the info I've been able to get from reading past posts has been tremendously helpful, I couldn't find any video help along the way. I've been trying to get it on video and I'll put it all together, maybe to post it (if I decide I'm not too big of an idiot on there, and if - the big if - I can get it to work!) I have a feeling I have a lot of editing to follow fixing the truck!

I can't believe the condition of these lines, and it seems like it isn't just my TB either! From all of the posts I've searched through on this topic, there are far too many with the same strange corrosion on the lines, and not just from places where salt is used on the roads for ice or near oceans.

Good luck with your TB, mine is an 03, and I have to admit that is be a bit worried about any high pressure flush of my tranny! Maybe if it were a later model, and not already leaking, I would consider it differently!
 

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Mine does the same, leaks from a trans oil cooler line... I couldn't tell where it was coming from because it was such a fine spray. I'm still not sure if mine is coming from the corroded pipe or the connector that is not replaceable.

I've tried quite a few 'tricks' to make it work, but since the last one failed, I've decided to cut it and put in the transmission hose.
Although the info I've been able to get from reading past posts has been tremendously helpful, I couldn't find any video help along the way. I've been trying to get it on video and I'll put it all together, maybe to post it (if I decide I'm not too big of an idiot on there, and if - the big if - I can get it to work!) I have a feeling I have a lot of editing to follow fixing the truck!

I can't believe the condition of these lines, and it seems like it isn't just my TB either! From all of the posts I've searched through on this topic, there are far too many with the same strange corrosion on the lines, and not just from places where salt is used on the roads for ice or near oceans.

Good luck with your TB, mine is an 03, and I have to admit that is be a bit worried about any high pressure flush of my tranny! Maybe if it were a later model, and not already leaking, I would consider it differently!
There is no high pressure flush. All the machine does is drain fluid from one cooler line as it refills from another. It doesn't flush or clean anything. But it does leave your old filter in place inside the pan.
 

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2006 gmc envoy_denali
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Good tip indeed
 

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Fluid type

Fluid change due, (last on the stuff needs done list) Opinions on Valvoline MaxLife synthetic LV..label reads replacement for V1 plan on replacing filter and disconnecting cooler line and doing what is termed "gentle flush" with a helper so as not run dry.

2002 Trailblazer 70K....Thanks
 

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Mine does the same, leaks from a trans oil cooler line... I couldn't tell where it was coming from because it was such a fine spray. I'm still not sure if mine is coming from the corroded pipe or the connector that is not replaceable.

I've tried quite a few 'tricks' to make it work, but since the last one failed, I've decided to cut it and put in the transmission hose.
Although the info I've been able to get from reading past posts has been tremendously helpful, I couldn't find any video help along the way. I've been trying to get it on video and I'll put it all together, maybe to post it (if I decide I'm not too big of an idiot on there, and if - the big if - I can get it to work!) I have a feeling I have a lot of editing to follow fixing the truck!

I can't believe the condition of these lines, and it seems like it isn't just my TB either! From all of the posts I've searched through on this topic, there are far too many with the same strange corrosion on the lines, and not just from places where salt is used on the roads for ice or near oceans.

Good luck with your TB, mine is an 03, and I have to admit that is be a bit worried about any high pressure flush of my tranny! Maybe if it were a later model, and not already leaking, I would consider it differently!
That's interesting to know, corrosion did not seem to be a big problem with this car otherwise, the body and exhaust held up great with a lot of winter driving.

Overall this was one of my favorite cars I've owned, and I was sad to have to get rid of it a couple of years ago, and envious you still have one! the front differential failed (after much extreme use) and is a bear of a job to replace on this vehicle- so it is enjoying a nice retirement as a 2WD somewhere in Florida.. I still see tons of them on the road so they are turning out to be great survivors
 
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