ATF fluid change dilemma- Change or not to change - PeachParts Mercedes-Benz Forum

benhogan · #1 03-08-2010, 12:04 PM

1973 220d has had the same ATF in it for at least 15 years.

It shifts fine and works fine. No leaks either.

I have been told not to change the fluid (this late in the game) as this will kill the tranny. Has anyone heard of this phenomenon?

Should I just drive it until the tranny dies.

compu_85 · #2 03-08-2010, 12:20 PM

It's an automatic? This is a tough call. How does the fluid look? How many miles are on it?

-J

Graplr · #3 03-08-2010, 12:24 PM

Change it.

SD Blue · #4 03-08-2010, 12:28 PM

Automatic transmission is an oil. From another perspective, would you not change the oil in your engine because it runs fine and hasn't been changed in 15 years?

Personally, I believe it's an old wives tale to never change fluids. If changing fluid caused a transmission to go out, it was already to that point.

SirNik84 · #5 03-08-2010, 12:52 PM

Quote:

Originally Posted by SD Blue

If changing fluid caused a transmission to go out, it was already to that point.

I have to agree with this. BUT, whatever you do, do not have the transmission flushed. a simple drain and fill is all you need to do. flushing can damag seals, and god only knows your tranny likely has weak seals after 15 years with the same fluid.

I'd drain the pan, then fill it, i wouldn't drain the torque converter, or change the filter, just yet. then get it hot, drive it around a bit. this will be your "wash water" after letting the new ATF wash your transmission, I'd then drain everything, change the filter and refill with all new fluid.

New fluid may hurt the seals, but if it does that they were toast to begin with. new fluid will protect the friction surfaces (clutches and bands) so if your seals can hold up, changing the fluid will be beneficial to your transmission.

tangofox007 · #6 03-08-2010, 05:00 PM

Quote:

Originally Posted by SirNik84

I have to agree with this. BUT, whatever you do, do not have the transmission flushed. a simple drain and fill is all you need to do. flushing can damag seals,...

I most cases, "flushing" is nothing more than a thorough fluid exchange, using the transmission's own oil pump. Compared to a "drain & fill," it cannot hurt anything but your wallet.

leathermang · #7 03-08-2010, 12:40 PM

That old myth has been discussed before...
in the archives if you want to read about it...

but the bottom line is ' change it'....

leathermang · #8 03-08-2010, 01:50 PM

I am all for changes of the fluid and filters... sometimes on old cars it takes multiple times to get rid of what has accumulated..then breaks away during the processes...
but I would include the torque converter in the original draining... if the FSM calls for that... and I am pretty sure it does.. otherwise you are leaving a significant amount of the old fluid in there to mix with the new ..
I would also add a can of Trans-X to the new fluid. If any seals are old and thinking about leaking this stuff swells them...
A few months ago I fixed a significant trans fluid leak on my 95 Lincoln ( a quart per 75 miles or so ) .. just by adding the Trans-X.... lots of threads in the archives about Trans-X....

latitude500 · #9 03-08-2010, 04:15 PM

Please, change both the oil and filter.

MS Fowler · #10 03-08-2010, 04:55 PM

You can find many people who say that fresh fluid will dissolve the accumulated varnish, and ruin the tranny.
I disagree with that, and agree with what has been posted above. ATF is an oil; change it ESPECIALLY if it has been burnt, or overheated.
If you transmission dies after a fluid change, know that it would have died anyway.

SirNik84 · #11 03-08-2010, 06:03 PM

If you take the car to a pep boys or other chain service center they normaly use a maching to pump the fluid out... at least thats what I learned in my AT class. also when I took a service writing course taught by a former pep boys service manager. Even if this is not the standard procedure at a place like that, I'm sure they would push it as an "up sale" so I thought I should just get the word out... if i knew nothing of how the transmission worked, a "pressurized scrubbing bubbles" type cleaning may sound like a good thing. especaly if i had 15yo fluid.

using the pump in the transmission to exchange the fluid does work well. and with some hose and a bucket you can do it at home.

DieselPaul · #12 03-08-2010, 06:16 PM

I too worked for pep boys a long time ago, it was nice to up-sell people $100 for the flush. I've heard that the pressure from the flush can break things loose and kill the transmission, I am on the fence, I've never had it done.

I am an advocate of doing a drop the pan, change the filter, refill fluid, and going. If the fluid was really nasty, do the same service again in a few weeks, so you exchange more fluid.

To the OP... I'd change the fluid and filter.

pawoSD · #13 03-08-2010, 07:39 PM

Change the fluid and filter right away!