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Discussion Starter #1
Hi All,

Apologies for the long post, but I like to provide context :)

I just bought a 2006 Yukon XL with the 4L60e transmission and I want to change the transmission fluid. I looked through maintenance records from the previous owner and it looks like the transmission was fully serviced (i.e. flush and refill) around 40,000 miles ago, at which point the shop put in VersaTrans ATF. VersaTrans is recommended for cars calling for Dexron III, but starting in 2006 GM called for Dexron VI in the 4L60e. The fluid still looks fine, very pink, no brown or metal, no burnt smell, but since it seems to be the wrong fluid for the car and it's been around 40,000 miles anyway I figured I'd just change it to be safe.

I'd prefer to do just a change as I don't think a full flush is necessary, plus I can do it myself and it's cheaper, and I'm a little wary of unintended consequences from a flush. I'm wondering what the best way to go about this would be. My drain pan doesn't have a plug in it, so dropping the pan will be messy. My first thought was to drop the pan, replace the filter and gasket, put in new fluid, and then repeat the whole thing in 1000-3000 miles or so. After dropping the pan and replacing everything twice I'd have a very clean filter and somewhere around 75% of the fluid in my transmission would be new stuff (planning on Valvoline MaxLife since it's flexible, should be compatible with whatever's in there).

Then I thought, what if instead I drained fluid from the dipstick. I have one of those cheap handheld fluid transfer pumps, it wouldn't be fast, but it would be cleaner. And, this way I could drain and refill multiple times before dropping the pan, which means I only have to replace the filter once, and I can get more of the new fluid in there (if I did this 4 times I'd have ~94% new fluid in there after the 4th time).

But, I've never tried this before, so I'm not sure if it'll work/be safe. Can I hurt anything by sticking a hose down the dipstick tube? If I didn't replace the filter until after changing the fluid multiple times would it get clogged up, or would repeatedly changing the oil this way cause crud to clog up transmission passages without ever getting to the filter? Basically, any danger in this method? Is there a better method out there? Would a full on flush be the right call after all? What have you done that's worked well for you?

By the way, I've read about the "redneck flush" that people have done, and I'm going to be replacing a cracked radiator so access to the cooler lines will be easy. But, I'm really trying to do things by the book and be somewhat gentle with this older vehicle, so I'm really not interested in going this route.

Thanks in advance for any advice you can provide!

Scott
 

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I am now on my 5th transmission fluid\filter change on my 2001 Suburban with 285k miles. I can do it now with eyes closed. LOL.
A couple of pointers learned from the experts here and myself.
1. On the pan with no drain, I would just disconnect the upper radiator line and insert a 3/8" OD x 3 inches long copper tube to the quick coupler on the radiator side then attached it to a clear hose. Put the hose in a 5 gallon bucket. Turn on the engine and it will pump out the dirty fluid. Stop when you start seeing bubbles in the clear hose. Save the dirty fluid.
2. You won't be able to remove the pan because it will hit the cross over exhaust pipe. You have to raise the transmission by about 1 inch (1.25" better). To do this, you have to remove the transmission mount bottom hex nut. Then raise the transmission with a jack and a piece of 2x4 to distribute the load on the pan. Once it's up, insert a 1.25 inch block under the transmission mount and cross member.
3. The shift bracket is also in the way when removing the pan. Some people bend it but I chose to remove the rear torx head bolt (T30? not sure) on top of the transmission and loosen the front one so I can swing it out of the way.
4. Once you are done with these 3 items, you can drop and pull out the pan with minimum amount of fluid.
5. Change the filter. Clean the pan. Put pan back with new gasket. Torque bolts in 3 steps. 50, 80 and 100 inch lbs.
6. Jack transmission up, remove the 1.25 inch block and lower it. Put the mount hex nut back and tighten to 30 ft-lbs.
7. Measure how many quarts of dirty fluid came out.
8. Fill up the transmission with same amount initially. You are done. Drive, get it up to temp, then check fluid level.
9. If you want to pump out the dirty fluid inside the torque converter, lines and radiator, do item #1, 7 and 8 but pump out and fill only one quart at a time. Do this until the fluid is clean.

I have been using Valvoline DEXMERC full synthetic fluid. It's Dexron VI.
 

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Others will chime in with their input, but basically think you'll be fine drawing as much as you can from the dipstick and then have the option to drop the pan to get what is there and change the filter - you will basically just be sucking from the sump anyway.

My truck is a 99 (owned from new) with a drain plug, so that side of the job is easier for me.

From all I've read Dex III and Dex VI are fully compatible so mixing in the system is not an issue. Personally, I think if you measure what you can pull from the sump via the dipstick, you can just do that job a couple of times until you are happy you have changed most of the fluid.

On mine, I have never done more than a pan drain and replacement every few years and have never had a transmission issue (knock on wood). However, I did do a valve body rebuild a few years ago when doing a filter change to update the actuators and put in a Transgo shift kit at the same time - not for any reason but just because the pan was off and the old girl was 16 and I pull a fishing boat over a steep hump several times a year, so I thought it worth doing as a preventative measure.

I haven't looked in detail at the 4L60e, but on a Saab we have the drain and refill method per the shop manual is to disconnect the output from the transmission cooler and, engine running, pump old fluid into a container, topping up with new every ~2 litres until the fluid runs new. That is simple on that car and I see no reason why it wouldn't work on the Suburban - just haven't looked at it.
 

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I think your research may be off a little, the VI designated fluid was formulated for the GM 6 speed transmissions (I assume that's the reason it was called VI), which were available in 2008 (I think, may have been 2007).
The VI fluid is backwards compatible; but I don't think it was in your '06 from the factory.

And yes, upgrading to VI is a good idea as the III may (depending upon the letter following the III) be prone to absorbing water, making it corrosive, and VI is backward compatible
With the intro of the 8 and 10 speed autos the formulations changed again and I don't know if they are backward compatible.

Changing it a few times will reduce the amount of III; but all you really need to do is to get rid of any water that may be in it. Personally, I'd change the fluid and filter, clean the pan and go on with life.

The only other thing I'd consider is adding a drain plug for the next time you change it.
 

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Well, I eat crow, I just downloaded your owners manual.........
It calls for Dexron VI to be used in your transmission.

But, does that mean it was in it from the factory, or did GM just want the owners manual to reflect the new product that would soon become the replacement for Dexron III, hmmmmmmmm?

Either way, the correct path is to now get VI in there.
 

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Discussion Starter #6
First off, thanks to everyone for the information and advice, it's tremendously helpful.

When I first started researching this I came across a site (which I've since forgotten) which derisively referred to draining the fluid through the cooler lines as a "redneck flush." However, after a lot more reading, and from your advice, this seems to be the accepted way to drain the fluid. Seems like the only concern is running the pump dry, which shouldn't be an issue as long as you shut off the engine as soon as bubbles appear in the drain line. I also found another excellent write up of the whole procedure here: How To: 4l60e Transmission Flush/Filter Change

About the only difference is that this guy added more drain/fill cycles to make it more like a proper flush than just a change. Obviously the benefit here is you get more fluid out, and the only negative I can really think of is the cost of the extra fluid required. Am I missing anything important here? Do y'all recommend one procedure over the other for any reason? Finally, if I did go with more of a flush than just a change but still wanted to drop the pan and change the filter, when would I do that? During the first drain/fill cycle? That would place the new filter in there for the remaining drain/fill cycles, although that shouldn't be too big a deal, right?

As an aside, don't feel bad RayVoy, I somehow got it into my head that my truck takes Dex 3 as well. I didn't realize my mistake until I was on the phone with someone from Phillips66 technical support and figured I might as well check the manual :) It does seem like it's the same equipment in 05 and 06 vehicles, not sure why the spec changed, although most people I spoke with seemed to think it was mostly for patent and/or marketing purposes. But yeah, going to Dex 6 (actually Valvoline MaxLife, which is approved for Dex 3 and 6).
 

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Discussion Starter #7 (Edited)
After some more thinking (I'm solidly into overthinking territory now) I've decided to keep things relatively simple. As far as I know there were no major modifications to the 4L60e transmission between 2005-2006, BUT, Dexron VI was created in 2005. It seems much more likely to me that GM decided to spec Dexron VI for the 2006 model year because it was shiny and new (and maybe worked a bit better than Dexron III), NOT because the transmission had really changed and could no longer use Dexron III.

So, while I still think it's a good idea to drop the pan (the shop did a flush for the previous owner and didn't charge for a new gasket or filter, so I'm guessing it's never been dropped) I think anything approaching a flush would be unnecessary, overkill, and maybe even risky on a car with nearly 180,000 miles. So, for the simplest, gentlest procedure possible, I think I'll drain through the dipstick, drop the pan, and disconnect the cooler lines (I have to anyway to change the radiator). That ought to get as much fluid out as possible without any high speed flushing action. The MaxLife is good for either Dexron III or VI, so should be fine with whatever's in there.

I'm collecting supplies this week and plan to do this over the weekend, I'll let y'all know how it goes.
 

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The switch to Dextron VI was due to improved fluid ability compared to previous generations Dex fluids. (Improved performance)

Some of which are:

Improved oxidation and thermal stability

Optimized frictional properties that provide smooth gear shifting during low temperature operation and help prevent transmission vibration

Outstanding resistance against sludge and deposit formation

Improved anti-wear protection which contributes to extended transmission life

Outstanding low temperature performance
 

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Discussion Starter #9
Thanks for the response udidwht, that's good information. I didn't mean to imply there was no reason to switch to Dexron VI, I would sure hope that it's better than Dexron III, otherwise what's the point of making it? I was just trying to point out that the transmission that ran just fine in a 2005 model with Dexron III would probably run just as fine in a 2006 model with Dexron III, even if it was no longer spec'd for it.
 

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Well, this has taken longer than I expected, but I'm just about done, I'm at the point of adding ATF back in. I measured how much I took out, which ended up being somewhere between 6-1/2 and 7 quarts. It's hard to say exactly because I couldn't catch quite everything in a drip pan, some ran off and dripped onto some old plywood I had put down. So far I have put 4 quarts back in, and when I checked the dipstick it was well above the cold mark. I'm assuming this is because the radiator, transmission lines, and maybe some other areas are empty, everything is just sitting in the pan right now.

So, I need some advice on next steps. I know I need to measure the level with the engine running and up to temp. Should I 1) add a couple more quarts in before starting it up to get closer to what I know is needed so it's not running dry, or 2) start the engine up first, hop out of the car, and then start filling again? I obviously don't want to run it dangerously low, and 2-1/2 - 3 quarts seems pretty low. On the other hand, I don't want to overfill it and have it blow out the dipstick. Any advice would be greatly appreciated here.

Oh yeah, one complicating factor. I also replaced the radiator, so I'm refilling coolant at the same time. I've done this before and am not too worried about how to do it, but I do know I'll need to keep an eye on the coolant level as it'll drop quite a bit when the thermostat opens. Trying to keep two different fluids topped off at the same time could be tricky.
 

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Good job if you reached this point.

Just start it up and let it run for 5-8 seconds to circulate the fluid then turn it off.
Add 2 more quarts of ATF.
Drive it to operating temp then check level.
Add ATF to correct level.
 
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