I have a question regarding changing trans fluid (no not a how to).

Talking to some people at work, and I seem to agree- It seems like changing trans fluid as maintaince is almost bad.

The three vehicles that had a slipping transmission that my family have owned have started to slip right after a fluid swap- or shortly after.

My subaru beater (sold now, 135k miles at the time) and minivan with 100k had no fluid swaps EVER and never a problem.

From what I understand, the new fluid will wear diffferently and cause slip problems due to the way the fluid flows???

It just seems like A fluid swap is a bad idea amongst higher milage cars if there has never been a fluid swap. however i guess that if it has been getting new fluid every 15k miles it wouldn't be so bad.


perhaps someone with knowlage in this black art can help us

 

That seems to go against everything one would consider logical.

If you think about it, the only difference between fluids would be a few factors to include viscosity. I would think that older fluid has the chance in its past of being heated to the point of breakdown on more than one occasion, which would lower its effectiveness in doing its job.

Not sure but while transmission fluid doesn't go through the riggors that motor oil does, I would assume that it has its point where it is no longer providing the protection that newer fluid would.

 

I've talked to my tranny man about this very subject, and he recommends that the fluid be changed without a torque converter change (effectively changing apox. half the tranny fluid per change. He told me that he gets trannys like the Mopar 727 in for a rebuild, and that the owner obviously never had changed the tranny fluid in a particular unit. He said the tranny was "caked" with powered ban material, and the filter was no longer functional. He changed half of the tranny fluid with recycled ATF and a new filter and the tranny took-off shifting perfectly with no slippage. He told me on a tranny with little service history that it is better to change half the fluid with a new filter, then go for half the recommended change interval, repeat and rinse...because detergent characteristics of tranny fluid that has a tendency to suspend whatever material clings to the interior surfaces and is suspended, sometimes clogging a filter and starving the pump sump will occur with a complete change....
On older, abused trannys, he often uses the recycled tranny fluid (lets it sit for about a month in a 55 gallon drum and the solids settle to the bottom) as an alternative to the new highly detergent stuff...
Just food for thought....

 

I used to work at a tranny shop and the reason why changing your tranny fluid can lead to tranny failure is IF your tranny is already failing.

The fluid inside is so thick and caked up with metal that is almost creating the necessary friction for the tranny to shift. When you flush out the tranny with this fluid that has all the metal in it, it tends to get stuck in places and create other problems that LEAD to failure.

So what i'm saying is that if you have a well built tranny and take care of it, changing the tranny fluid wont harm it. If the tranny is already in trouble and possibly damaged....ride it out until it completely breaks

 

In order for prevenitive maitinece to work on a daily driver, it has to be done regularly. Not done when the fluid looks like mudd, your asking for it! Thats what recommended service intervals are for. When you got a 100k + mile trans unmaintained your on borrowed time. Then the fluid gets changed & there's a problem?