As you might know my 94 just got a reman GM Goodwrench 4t65e put in by a tranny shop in my area. The owner called me again to appologize for his behavoir when i picked the car up last saturday and wants the car to come back in 20,000 miles for fluid flush and filter change , he wants to do it for free .

Is this ok to have it flushed @ 20k ? I wont take it there to have it done as id rather have My local Cadillac Dealer do it for me ....Just wondering as we all know it isnt a good idea to flush a tranny with alot of mile behind it and i wonder what to do with a reman tranny....

Also im doing a breakin proceedure of no more than 55mph for 500 miles with very gentle takeoffs from a stop(like a new car) , no one told me to do this i just decided to do this on my own....Am i being paranoid ?

So far 147 miles on this tranny , i want another 149,853 out of it

Why would a new trans require fluid change/flush that soon? Drive it and forget about it. In any case, never have it flushed or let anyone flush the transmission. Drain the fluid, replace the filter and refill. Forget the concept of flushing. Read the archives if you need more reasons..

Thanx for the reply , i saw the archives but it left me wondering about a new or reman unit...Flush is just plain bad perioid .....

The trans "flush" is actually a misnomer...there is no chance of causing any damage to a trans from a complete fluid change...it is rather like dialysis for your trans. Our machine is basically a metal cylinder with a rubber diaphragm in the center. The machine is filled with apx. 16 qts. of fluid, which rides on the top half of the cylinder. As the dirty fluid enters the bottom of the cylinder, an equal amount of new fluid is pushed back into the cooler, and continues the cycle. There is actually a sight glass where you can see the fluid go from dark brown(on a really dirty car) to bright, clear red, and the whole procedure takes about 15 minutes. I have yet to see this procedure damage any vehicle. The horror stories usually arise when someone tries to fix a mechanical trans problem with a power flush machine that uses air pressure or external pump. This machine has no pump, all pumping is done by the transmission pump while the vehicle is running. What could be better than changing all of the fluid in the trans instead of the 5 qts. you effectively change by dropping the pan?

Using a machine like that for a simple fluid exchange is fine I would say.

The problem is that generically the term "transmission flush" tends to cover anything from the machine described to a power flush or back flush or any other sort of machine that hooks up to a transmission. Most of them CAN cause problems if the fluid is not clean, lines are hooked up correctly, backflushing puts debris into the wrong places, etc. The only way to avoid the "bad" machines is to avoid transmission "flushing" period.

It is perfectly fine to simply drop the pan and change the fluid available. On a 4T80E there is much more than 5 quarts that will come out when/if you drain the sidecover also using the "hidden" drain plug for the side cover oil.

As has been stated before, the best compromise is to simply loosen one of the cooler lines, start the engine and let it idle and let the trans pump it's own fluid into a bucket thru the loosened cooler line while fresh fluid is poured into the unit. This will change the majority of the fluid without subjecting the trans to any outside equipement or chance of contamination.

I reviewed all the trans "fllushing" machines on the market several years ago at the SEMA / AIES show in Las Vegas specifically for the reasons mentioned above. I saw first hand that there are a number of different machines that use a variety of methods to "flush" transmissions ranging from simple fluid exchange to complete flush with solvents, air pressure, reverse flushing, etc. From what I saw there are many ways that a mis-informed tech could screw up a trans with the equipment or an unscrupulous shop could cut corners with used fluid, recycled fluid, filtered fluid, etc. The only way to avoid it is to avoid the machines. If you must flush then make sure you thoroughly understand how that specific machine works and how the mechanic is error proofing the process to prevent contamination or use of old fluid.