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Changing Transmission Fluid After 100K Miles

03Z71Yellow

Full Member
Joined
Apr 21, 2010
Messages
25
I've got about 101K miles on my 03 Z71.  The transmission fluid has never been changed.  I was going to do this as part of my 100K mile maintenance.  I've heard from several people that if I've not had my fluid changed periodically up until now, I'm better off leaving the old stuff in.  Can anyone share some thoughts on both leaving as is and replacing?
 
tagging this post as i'm also interested in feedback.  I bought my truck with 113k on the clock, and have no idea if the original owner kept the tranny flushed periodically.. 
 
Oils are oils and all oils break down over time.
Oils in good condition also aid in prolonging various seals and gaskets.
The only reason for not changing your fluid is if you are going to divest yourself of the Av.
If you are going to keep the Av for a long time ~100K is a good time to flush and change the transmission fluid.
I let my transmission go to 125,000 and an evaluative check of the fluid indicated it was no longer in good condition.
You might also look into other service - diff's, radiator fluid, etc.
Expensive, yes, but being proactive helps push eventual repairs out to higher mileages.
 
100k on any transfluid is a lot, don't be surprized to find the black nasty slime on the bottom of the pan.  I would not have it flushed with that many miles as some flush machines force fluild places and directions it normally doesn't go and my stir up debris and push it where it shouldn't be.  Even if you drop the pan install new filter and refill the color will not be much different as you are only changing 1/3 of the fluid but it is better doing nothing.  I pull the drain plug on mine every time I change the engine oil and pour in 3 3/4 quarts and replace the filter every 30k and at 77k my trans shifts better than new.  I also use dexron 6.  Good luck
 
I would definitely change it and consider having it forward flushed. Never back flush a transmission for the reasons just noticed. Imo, whoever invented that concept is a masochist or in the business of selling tranny rebuilds....or both.
 
Did a drain and fill via the drain plug at 30k miles, and did a filter change at 100k miles, both times it looked great.

Change it.
 
                              The manual recomends 100,000 miles. My fluid was burnt @ 50k. The fluid must withstand alot of heat, which causes the fluid to get burnt.New fluid will aid the clutches and disc.I would replace sooner if needed. A fluid change or fluid and filter change are ALOT cheaper than a new transmission.
 
I'm on the fence about this as well.

141k on the clock, bought her with 68k.  Not sure if it was ever changed by the previous owner(s), but I know I've never changed it.  Has had a large aftermarket tranny cooler on it since I purchased it.  Since about 135k, I've reprogrammed the tranny slightly with HP Tuners...I didn't change any line pressures, but just increased some shift speeds and made some minor tweaks on how long it will hold a gear in the towing mode, as some of the factory settings have annoyed me a lot ever since owning it.

Tranny doesn't slip or have any issues whatsoever - and never has.  Fluid is still pretty red.  I've probably added 2-3 quarts to it since I owned it (about 1 when I did the cooler, another 2 from a leaky hose clamp I repaired).   

I fear changing the fluid will just cause me issues.  I tow short distances with it very often in the summer (around 5000lbs), longer distances once in a great while.

I just can't decide of which gamble to take - the leave it alone gamble or change the fluid gamble.  I wouldn't do a flush, but rather pull the pan (clean it + new filter), then pull the output of the tranny cooler hose and fill new fluid in the dipstick tube as old fluid comes out the cooler method.  I would love to NOT spend money on a new tranny this year. 
 
I did mine with over 100k and its fine now at 146k.
I wouldn't just do a flush and fill but also drop the pan and replace filter and as much fluid as possible
.
 
Do the 2007 up Avalanches come with a plug in the pan for each draining?  I've got 75,000 miles on mine and have been wanting to drop the pan and replace the filter.  A drain plug would make it a much easier job.  Also, what filter should be used?  Any tricks/tips to dropping the pan?  Any other areas fluid could be drained from to get more fluid changed out?  I have had nothing but problems when flushing past vehicles.

Thanks.
 
I too have this issue. Just purchased my 03 2500 with 103,000 on it and of course came with no service records. Thinking bout just draining as much fluid as possible n replacing filter. Curious if the filter comes out quite easily. Once on my 94 fullsize blazer I tried to replace filter but could not get the plastic gasket piece that went over inlet neck out of housing. So i left it in and jus put new filter in....tranny went about 3000 miles later and found the filter floating in pan! Obviously I've learned from younger less knowledgeable mistakes. So does anybody know about the filters in the 4l80e???
 
woyster_07avy said:
Do the 2007 up Avalanches come with a plug in the pan for each draining?  I've got 75,000 miles on mine and have been wanting to drop the pan and replace the filter.  A drain plug would make it a much easier job.  Also, what filter should be used?  Any tricks/tips to dropping the pan?  Any other areas fluid could be drained from to get more fluid changed out?  I have had nothing but problems when flushing past vehicles.

Thanks.

My 08 didn't have a drain plug. I'm a firm believer in 50k mile trans fluid changes though. My truck just clicked 100k and I serviced it and transfer case. I let the t-case go 100k and will never do that again, it was completely black. Those of you who have let it go to long, I would just drop the pan and get all the gunk out, do a filter change and fill it back up. Transmission flushes are not recommend. I have seen several cars not move after a fluid flush and change.
 
woyster_07avy said:
Do the 2007 up Avalanches come with a plug in the pan for each draining?  I've got 75,000 miles on mine and have been wanting to drop the pan and replace the filter.  A drain plug would make it a much easier job.  Also, what filter should be used?  Any tricks/tips to dropping the pan?  Any other areas fluid could be drained from to get more fluid changed out?  I have had nothing but problems when flushing past vehicles.

Thanks.

I have a Mityvac 7201 Fluid Evacuator Plus for changing the oil on my Mercedes and it works great for sucking the trans fluid out of the dipstick tube as well.

http://www.amazon.com/Mityvac-7201-Fluid-Evacuator-Plus/dp/B0002SR7TC/ref=sr_1_7?ie=UTF8&qid=1333056649&sr=8-7
 
ive found that if you have alot of miles its safe to do a filter change then within do a flush. introducing bran new fluid to an old tranny usually causes leaks. Filter adds some new and if you have no leaks try the flush or do a drop and fill
 
This weeked I changed the filter in mine. Just over 75000 miles and the fluid still looked very good. I used a small vacuum with hose stuck down the fill tube and was able to suck about 2 qts out before dropping the pan...didn't spill a drop till the pan hit the exhaust and I dumped the contents all over the garage floor! I plan on getting a smaller hose and using the vacuum to pull out and replace fluid every oil change from now on.
 
50 to 75k is the suggested interval for trans service with filter change.  It depends on how hard you drive your vehicle and under what conditions. It is highly recommended for those of us not mechanically inclined or have a full service bay at the homestead. As I have learned over the years, take care your equipment and it will take care of you.
 
I have changed mine 4 times in 189k miles. This has kept my tranny running good. After the last change my tranny showed very little wear and nothing beyond normal. But remember if it says change every 75k I will go 50-60k. I change my Syn oil every 3-4k instead of 5-7k. I don't mind spending a little extra to save a lot in the future.
 
So far, I've changed mine three times in 106K miles. I plan to do the next one in May before the summer heat begins.
 
Now is the perfect time to have it done. You rather know now, then find out later. If you are worried, then take to a transmission service for have them check it out.
 
We just bought our Av with 130k on it, aparently it hasn't been changed so I'm going to have a flush done on it. I guess they should change the filter too.
 
Rewind said:
We just bought our Av with 130k on it, aparently it hasn't been changed so I'm going to have a flush done on it. I guess they should change the filter too.
I have heard (only here say) that flushing the tranny may cause a host of other issues if it is done for the first time at a high mileage.

From what i understand, flushing MAY dislodge particles that have been resting in the fluid and place them in inappropriate areas.

It is recommended you drop the pan and change the fluid from there.
 
I've heard that too. Just wasn't sure which I should do.

So just draining and doing a filter change will be ok?
 
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