New AC Delco Dexron VI Synthetic ATF???

[Chubbs]

Depending on how many miles you have on your truck, if it's more than 60K and you never flushed (vacuumed) it before, don't do it !! My truck had 100k on it, ran beautiful, i decided to have the tranny flushed using the machine, 2 days later, tranny burned out. I believe the flushing loosens up particles that then get stuck in the valves etc.

I have heard lots of these stories. I don't know what is involved with that process or exactly why it happens but it has happened to folks with 100k + miles on a complete transmission fluid replacement. I just bought a truck with 125k miles and I'm going to drain the pan and replace the 5-quarts or whatever comes out with AC Delco Dex6. I will do the same thing again in 6-months, and maybe drop the pan & replace filter + 5-qts next year. I have been debating how to go about it since purchasing the truck last week and your comment helped make my decision.

 

[Chubbs]

Depending on how many miles you have on your truck, if it's more than 60K and you never flushed (vacuumed) it before, don't do it !! My truck had 100k on it, ran beautiful, i decided to have the tranny flushed using the machine, 2 days later, tranny burned out. I believe the flushing loosens up particles that then get stuck in the valves etc.

Can you go into more detail on your experience with the trans failure? Make/model of vehicle, the business or type of business that performed the exercise, type/brand of fluid used compared to original fill, number of miles between the work and onset of symptoms, etc.
what were the initial symptoms of trans failure and time until complete failure of the unit? What steps did you take after the vehicle came to be DOA? I have many more questions that resulted from the failure and if/any results were requested or given as to the nature of the failure and extent of damage. Any advice or directions provided to you in regards to future service of the transmission. Thank you.

 

[Churchill]

NO!!!
Not if you have the "auto 4x4" button on the top: AC Delco Auto Trak 2 for these transfer cases.

Chubbs, that's what I thought, thanks for the confirmation...

 

[Churchill]

I have heard lots of these stories. I don't know what is involved with that process or exactly why it happens but it has happened to folks with 100k + miles on a complete transmission fluid replacement. I just bought a truck with 125k miles and I'm going to drain the pan and replace the 5-quarts or whatever comes out with AC Delco Dex6. I will do the same thing again in 6-months, and maybe drop the pan & replace filter + 5-qts next year. I have been debating how to go about it since purchasing the truck last week and your comment helped make my decision.

My truck is a 2001 GMC Yukon 4x4 SLT. When it turned 101k miles, I was preparing for a cross country trip towing a trailer so I figured I would change the tranny fluid for the first time ! Yes, way overdue, but we were monitoring the state of the fluid all along and it was fine. I brought the truck to my local shop. He told me that he would evac the system using his machine. Unfortunately I did not do any research, just gave him the go ahead ! I don't know what fluid he put in. I picked the truck up drove it to my house about 15 miles. The next morning I get in to drive to work and it would not shift out of 2nd, I slowed down and limped it back to his shop, where we lost reverse also. He pulled the pan and filter, which from my understanding he did NOT do on the original job, don't know why ?? Sorry to say, he could not get it back to life with another flushing, the damage was done. After the fact I find out from a cousin of mine who owns a "junk yard", ever since the local Goodyear shop bought an evac machine, his request for transmissions tripled in one year, and he's owned the shop 20 yrs, so he knew the norm. Another sad ending of the story, my extended warranty expired at 100k ! So $3200 later i'm on the road again. Happy to say my truck runs like a tank, now has 200K, this time I will only drain the pan and replace the filter !! Sorry if it's long winded...I hope it helped !! I would follow exactly what your plan is...

 

[Chubbs]

I really don't think that I have the best plan, just FYI. I like to exhaustively research subjects such as this before doing anything, whatsoever. From what I have learned so far, most techs advise that if your trans fluid is pink to light red & still has the normal odor then you are "probably" OK to do a flush. If the fluid is dark red or almost black & has a burnt odor then a flush is not for your application. Reason being that the flush or "complete fluid replacement" is removing the old fluid which contains the particles and contamination necessary for the clutch plates within the trans to continue operating. Once you remove that contaminated fluid the clutch plates begin to slip due to loss of friction that the parts had when suspended in the original fluid. Furthermore, the machine used can also ruin an otherwise good trans with good fluid by contaminating it with someone else's waste fluid due to the machine and operator error/carelessness. From what I have read, any trans fluid over 60k miles may or may not have the characteristics of this suspended particles in combo with worn friction plates being disguised as such. If fluid color & odor tells the tale then based on your observations 1 should be of the notion that the machine used in your flush was contaminated itself, resulting in damage to the trans. But principle would say your clutch plates were already worn out because your original fluid had broken down and the fresh fluid only exposed an underlying issue. I don't know, every story gives me pause to reflect. I paid cash for my vehicle so I'm not going to have a bunch of extra cash laying around. I can't make a mistake.
If you know where you are starting off then it's safe to flush the trans but I'm almost scared to have it done anywhere. My best case scenario for a full-fluid exchange is DIY with a modified outlet from the trans cooler to a bucket where I would then start the engine, let the trans pump most out, then start adding before the went dry. In this scenario I know I'm not cross-contaminating the trans, the best/proper fluid is going back in it and so forth. I'm going to keep asking reading & asking questions. The $25 carfax may also be worth the cost, especially if a trans servc shows up somewhere in the history. I would feel much safer doing a fluid exchange with that documentation. It's a 125k mile truck from 2003 (Yukon, like yours, 4x4/3.73 gear/g80 locking dif) If that's the actual mileage, I don't know; vehicle history report could come in handy there as well if the dealer sold me a 200k mile vehicle with mechanical issues.
PS: owned a 2004 LR Discovery & did a couple fluid drain/refill with pan drop & new filter 2nd time at around +\- 100k miles. It was dealer maint with a "sealed trans" and I experienced no ill-effects servc tranny in that manner.
Sorry to hijack the posting.

 

[sefiro]

In general, the only time to use a pressure fluid change is on normal maintenance when the fluid is still pink - but then, the tranny doesn't really need it. Otherwise,a pressure machine can stir up stuff, backwash a filter ( putting material into valve body ), blue a filter.

A true evac machine will draw fluid from the pan but only on those trannies that have a full pipe that directly accesses the pan. This will only remove half the fluid. Refill, Evac 3 times and you can get roughly 90% exchange.

Diy through the cooler line will prevent pressure problems and get nearly all of the old fluid out. Keep adding fluid while in neutral until you see clear red fluid in the drain hose.

Ideally, diy until 1 gallon is out, start adding 1 gallon new, and run until 2-3 gallons out, drop pan, replace filters. Add two gallons, start engine and run another gallon at least it ensuring clear fluid, then top of as necessary.

As for old dirty fluid change, if it's really dirty, then you are already headed towards a rebuild. The dirty brown fluid is not providing lubrication, is creating additional friction on clutches, interfering with pressures allowing for slipping of the band etc. Assuming no other problems other than old fluid, a diy should be fine - but more often than not - the damage had already occurred and you are running on borrowed time. Plenty of 150k+ trannies out there with pink fluid.

Sent from my XT1053 using Tapatalk

 

[6OhDenali]

After reading all this its making me nervous to do mine as well. Right now my tranny feels fine..i thought i noticed a slip only once when it downshifted when i gunned it from 60mph one day. Tried to repliacte it and never happened since. I bought a much bigger cooler and filter, and fluislds. Was gonna do mine this weekend.
If i drop my pan and replace the filter and the 5qt that comes out of the pan, wait a week and do it again, will that get a good amount of the old fluid out? Mines still pink and doesnt seem to have any metalic flake in it.