Opinions on doing a transmission flush vs. Fluid and filter change

[2 De River]

I have a 07 GMC Seirra p/u with 4.8 v8 engine, 70,000 mi. I am not experiencing any problems but it is time for transmission service. I have contacted several shops in my area and find most of them to be using the flush method. I have never used this type service before. I have asked a of techs and they brought up one point that kind of makes sense, they say that the flush method takes care of all the fluid including the torque converter, where a drain and fill would still have some old fluid in the converter. Then there is the question of the filter, I have been told that the flush method also cleans the filter?

What are your opinions? What method have you used? Thanks! Jimmy

[Bies]

The flush method removes alot more sediment, and also takes the worry out of air locking the metering plate where the filter goes,
I have changed fluid in old high mileage cars, and sometimes they will not move after the change.

[rock]

A good friend is a Ford tech and I have watched him flush mine several times. His machine has a site glass and you can watch as the fluid goes from brown to red. I would think just the movement thru the system with clean fluid would have somewhat of a scrubbing effect plus all the advantages you have already stated.
Rock

[allstock]

Do both. have the pan dropped,cleaned,and change the filter.Than run a flush on it. IMO, it is better to change the filter,and inspect and clean the pan, then worry about changing ALL the fluid. Use Dexron VI, the 4l60-e's like it. 25 years in the transmission fixin' business, 20 as shop owner.

[Bies]

Good response, I like that. Do you hook up to the cooling line?

[Erine]

Agree with allstock been in this buisness for 30 years but if your only going to do one flush it and get the fresh fluid.

[allstock]

[QUOTE=Erine;2251699]Agree with allstock been in this buisness for 30 years but if your only going to do one flush it and get the fresh fluid.[/QUOTE
Oh Sure....Just had to up me by five years...lol

[Erine]

Thats funny, but you are right on, a little pricey but the only way to do a complete service

[Ted Stryker]

Do both. have the pan dropped,cleaned,and change the filter.Than run a flush on it. IMO, it is better to change the filter,and inspect and clean the pan, then worry about changing ALL the fluid. Use Dexron VI, the 4l60-e's like it. 25 years in the transmission fixin' business, 20 as shop owner.

I agree... Maybe one day they'll have spin-on filter...

[jeepster21]

I agree also..Do the filter then flush it..
But then again what do I know. My GMC has been through 3 transmissions in the last 15,000 miles

[Ron V]

I would NEVER flush an automatic that hasn't been touched in that many miles. The guy who rebuilt one of my transmissions has been in the business his whole life and he was of the same opinion. The only way I would ever flush an automatic is if I did it ever 10,000 or so. It's a sure way to dislodge a bunch of crap that would otherwise have gone undisturbed. I can't think of a more asinine thing than to purposely break the crap loose from the filter. I remember the first time a dealer told me that was how they do it - I almost sh@t. Drain and refill. Even if you have to do it a couple of times so that it helps get what was left in the torque converter, it's better than taking a chance.

I think allstock has the best idea, if you're going to flush it at all.

I don't flush my cooling systems either, for the same reason. My opinion only.

[Ted Stryker]

Why does flushing break anything loose..? Again, I'm no trans tech and this is an honest and unloaded question but it seems like it is simply introducing new fluid where old fluid used to be... I could see if it was a higher than normal line pressure with the flushing unit or some sort of agitating flow, but it just seems like it replaces the old fluid at the rate that the trans would be moving the fluid anyway...

BTW-- Are you just referring to flushing with an old filter, because I wouldn't do that either... I agree to change the filter first then flush...

[T-REX]

I agree wit tha pan removal, filter change, and flush.....Thats tha only way U kin git tha ole fluid out tha converter(unless it haz a plug, sum do sum don't)...Most also have a magnet in tha pan that needs cleen'in...not ta mention all tha sediment in tha pan(normal clutch wear)...Juss my unprofessinal opinoin!!

[Forkin' Crazy]

Well, does the fluid break down? Not that I really know of unless it has been severely abused. If you have brown fluid, you have more problems than a flush will fix. Transmission fluid is about the same as hydraulic oil. I have used hydraulic oil in an auto transmission. I never change the hydraulic oil in my tractors unless we have to tear the transmission down. I change the filters once and year and that's it. Just like I do on my auto trans in my truck.

[Fulltilt]

Breaks loose medal particles and dirt.

Was told by a very good trans tech not to flush trans on high mileage vehicles that haven't had it done, as part of the regular maintenance.

Sold trans flush once to a customer with a full size van with over 100,000 miles on it. Never had it done before, and the trans went out with in a week.


Why does flushing break anything loose..? Again, I'm no trans tech and this is an honest and unloaded question but it seems like it is simply introducing new fluid where old fluid used to be... I could see if it was a higher than normal line pressure with the flushing unit or some sort of agitating flow, but it just seems like it replaces the old fluid at the rate that the trans would be moving the fluid anyway...

BTW-- Are you just referring to flushing with an old filter, because I wouldn't do that either... I agree to change the filter first then flush...

[Ron V]

Why does flushing break anything loose..? Again, I'm no trans tech and this is an honest and unloaded question but it seems like it is simply introducing new fluid where old fluid used to be... I could see if it was a higher than normal line pressure with the flushing unit or some sort of agitating flow, but it just seems like it replaces the old fluid at the rate that the trans would be moving the fluid anyway...

BTW-- Are you just referring to flushing with an old filter, because I wouldn't do that either... I agree to change the filter first then flush...

They flush it at high pressure with a reverse flow, to back all of the particles out of the filter. At least that's the way some of them are done.

[Instigator]

I've changed fluid/filter on every high mileage car I've ever bought. I install (about $7. at the pts store) a drain plug for next time too.
Never had an issue w/any of them. Mama's Blazer is an '00 that we bought (one owner) w/230K on it. I did the fluid/filter and it just turned 250K w/zero issues.
The shops love the flush cuz it's quick and makes and easy sale. 15 mins and almost any of their oil change guys can do it Vs dropping the pan/filter.

[Greg G]

Funny that the subject of flushing came up. I have a 2006 Volvo V70 R wagon with the 6 speed auto. I'm getting some feedback from the tranny mostly on final stop (small thump) and when grabbing 2nd (pause then slam) and I was thinking it would be worth trying a full flush even though it is a "closed" system according to Volvo. I'm figuring that those noises are not good anyway and maybe the full flush will help for a bit?

[Ted Stryker]

They flush it at high pressure with a reverse flow, to back all of the particles out of the filter. At least that's the way some of them are done.

I don't think I'd want a flush if it used a reverse flow or higher than standard pressure...

[Ron V]

I doubt it's any higher pressure than what normally develops in an automatic under use.

Put it this way...the flush is something that is pushed hard by the quick lube places and also the dealers. How could it possibly be any good?

[johnboy 88 vegas]

About 6 months ago my mom took her 05 Expedition to the local ford dealer and they talked her into flushing it with about 80,000 miles on the odometer. Well guess what happened one week later. Thats rite it was back in the shop for a remanned transmission. Have heard nothing but horror stories about transmission flushes with the exception of one person I know who has 300,000 miles on a 97 F150 and has had his transmission flushed four or five times already. Guess its a flip of a coin weather its gonna work or not.

[Forkin' Crazy]

I doubt it's any higher pressure than what normally develops in an automatic under use.

Put it this way...the flush is something that is pushed hard by the quick lube places and also the dealers. How could it possibly be any good?

It is snake oil, just like nitrogen in your tires!