Hey Guys! I have a 99 Z28 and a 1990 Cadillac Eldorado for a daily driver. I visit a cadillac (www.cadillacforums.com) message board from time to time. There was a recent post about trans flush's and how they're actually bad. I've had 2 trans flush's on my Camaro and 2 on my Caddy and have had absolutely NO problems. The only bad thing I heard was a trans flush may cause problems if you've never had your fluid flushed on a trans with 100,000 or more miles. These guys in the Cadillac board seem like real morons sometimes. They really just pull stuff out of their ***.

What do you guys say?

Thanks!

 

I think it depends where the fluid is pulled & reintroduced.
If it goes in the "normal" flow direction and is up by the
radiator cooler then it's not one bit different from normal
operation. Now, if you get Cooter hooking the hoses up
backward 'cuz he can't read the pictures, then who knows?

I had one done and it was a hell of a lot less bad, than
letting the B&M juice sit in there one more day.

 

Because ATF fluid is very high in detergents, if you have a high mileage tranny with old burnt fluid in it, the new fluid with fresh detergents can break loose a lot of the sludge and varnishes that are coating everything and cause problems. If your tranny is regularly serviced and the fluid has never been burnt, there should be no problems with a complete tranny fluid flush.

 

It is a good thing. There is an myth that you should not flush fluid in older cars because the fluid is helping the trans live but that is BS.

 

My 90 Eldorado only had 24,000 miles on it when I bought it April 02. At 30,000 miles I had the trans flushed and had no problems, even though the fluid was 12 years old!!!

That just re-inforces your statement!

Later

 

Here is what this one guy had to say on the Caddy message board! This guy always has something educated to say, although his info never works in real world experiences as far as I'm concerned! I'd like to see what this guys qualifications are and where he gets his info!


<<<<Never, ever flush a trans. There is no "safe" way to flush a trans unless you own the flush machine and control it yourself.

Flushing a trans has several pitfalls...

The most obviuos is that the last vehicle hooked up to that flushing machine probably was on it's last leg and was generating tons of debris. Most owners, when the trans starts to act up, rush to get a "flush" in the fervent hope that it will cure the problem. So....flush machines, by definition, see the worst of the worst. If the lines aren't cleaned, hooked up improperly, oil is reused or recycled, etc....then you are screwed as your trans gets the dose of debris from the last trans. No matter how good the intentions of the shop, one simple mistake and your trans gets the debris.

Flushing is supposed to negate the need for removing the pan, cleaning the debris and replacing the filter.....BS. There is considerable debris coating the inside of the trans pan with miles as anyone who has done this can attest. That is part of the maintenance, removing the pan, cleaning the screens and replacing the filter and cleaning the pan.

All that debris in the pan is laying around in areas where there is little oil flow by definition...it tends to settle in the areas where the oil is quiet and just lies there not hurting anything....until the "flush" stirs it up and circulates it thru the trans. What a concept....LOL

Reverse flush.....?????.....what logic makes anyone think that it is a good idea to reverse the oil flow path in a reverse flush and flush sediment and debris into areas that are normally protected by filters, etc...???? Stupid idea. Period. No other way to describe it.

"Transmission flush" machines are money makers for the shops and dealerships because they are quick and easy and they can actually charge more money for it under the guise of it being "better" for the trans....when it is really a detriment....suckers born every day......

Read the factory service manuals and point out the place where a transmission "flush" is recommended.

So what if all the oil cannot be removed. A "flush" doesn't remove it all either.


If you really really want to replace as much oil as possible in the trans, drain the pan, service it by removing/cleaning/changing the filter and reassemble. Refill the trans with fresh fluid. Disconnect one of the cooler lines at the radiator, put it into a bucket and start the engine. Let the trans oil pump purge the old oil into the bucket so that nothing is subjected to abnormal oil flow. Start pouring oil into the trans to keep it full while the idling engine/trans oil pump purges the fluid thru the system. Easy and quick and gets ALL the fluid out....and eliminates any risk of hooking up to a "flush machine".


I know this is about 4.1/4.5/4.9 engines but be aware that on the Northstar engines/4T80E transmissions there is a hidden drain plug for the trans side cover that requires that the bottom pan be removed to drain the side cover oil storage area. The idea of flushing a 4T80E is even more ludicrous than a 4T60 trans for this reason.

The 4T60 and 4T80 transmissions are similar in that both store oil in the side cover...but they do it differently. The 4T60 trans with the 4.x engines stores oil in the side cover only when HOT. There is a bimetal thermostatic valve that closes causing side cover oil to be trapped behind a wier or dam. So, change the oil in a 4T60 trans when it is cold to get the most oil out.... The 4T80 trans is a dry sump unit that ALWAYS stores it's oil in the side cover. There is a scavenge pump that scavenges the oil from the bottom pan to the side cover all the time. That is why there is a hidden drain plug underneath the bottom pan to drain the side cover when the pan is off for service.

Guys....FORGET THE IDEA OF FLUSHING YOUR TRANSMISSIONS. Normal trans maintenance is a good idea. Drop the bottom pan, change the filter and clean everything up and refill the trans with fresh fluid. Do the cooler line/bucket purge if you are really fastidious about changing all the fluid.....but....DO NOT hook your trans up to a flush machine.

Really now, would you get a blood transfusion from an unknown source that is reusing needles......about the same thing if you think about it. A flush will do absolutly nothing more than a good drain and refill will accomplish...and potentially a lot of harm. Do not take the risk. Just because some have had good experiences (or the lack of a bad experience) with a flush does NOT mean that they will always go good.>>>>


By the way, I change my filter. I don't leave the old one in there!

There it is! What do ya think?

Later

 

Tell that guy to get his trans flushed by a place that uses new fluid.

 

i have seen two trannys fail after they have been "fully" flushed. one of them was my friends '02 ws6. its a toss up i guess.

 

Well there is probably more to that story regarding your buddy's 02 WS6, either it was not topped up right or the trans was already failing.

Keep in mind that there are different transmission fluids out there and different friction modifiers.

 

Especially if you're flushing it because it's already
showing signs it's hurting, it would be hard to say
the flush caused anything that wasn't already
coming your way.

 

well if you think about it, when you put a new verter and a shift kit in, on a A4 car with XX miles, you're replacing alot of old fluid (Care to guess %%?) with new Fresh detergent fluid.

so you screwed anyways, right? I'd guess 90% of the fluid being new and full of detergent is enough to slough off some old varnish by itself.

maybe its just russian roulette.

 

A lot of times folks try to flush burnt fluid and see if that addresses a tranny problem. It's usually way too late. You can do things like run 1/2 Dexron and 1/2 Type F and maybe some Lucas modifier, that's Mike @ Yank's one suggested cocktail.