1996 GL AT Fluid Change

Hi! I have a 1996 GL with the 3.8L and 142k miles. To my knowledge the transmission fluid has been severely neglected as I have had this van since ~39k miles and sorry to say it has not been changed. Wanting to change my bad habits, I thought of changing the fluid and the filter; however, I've read nightmare stories about how new fluid is less "gritty" and oftentimes new fluid causes an old transmission to slip and be severely damaged in < 1k miles! I was thinking about easing the system into a fluid change following the advice in this thread about the 50% change (mid way down first page):

http://www.automotiveforums.com/vbulletin/showthread.php?t=382406&highlight=fluid

Any thoughts? I don't know if I have a real tranny problem just yet. I get some shudder in overdirve on occasion and maybe once a month a hard shift but no real slippage in which I can sense a RPM change.

Thanks.

I think it is safe to say that new tranmission fluid OF THE CORRECT SPECIFICATIONS has never hurt ... rather, has always helped the life of a transmission. Check your glove box manual for the proper specs ... yours probably uses MERCON, not MERCON V. But I'm guessing.

Now, a tranny can be damaged by improper fluid change-out. There are many who would disagree, but I believe the machine flushing that so many shops promote is risky....

I believe the old time proven method of dropping the pan, cleaning the pan and pan magnets, replacing the filter, and installing fresh fluid .... just as described in chapter 1 of the Haynes manual .... is the way to go.

Note: Some year models have a reusable tranny pan gasket ... not sure about the '96.

The '96 uses Mercon (Do NOT use Mercon V).
I use Mobil 1 ATF which is Mercon. You can get it at Autozone and many other auto parts stores.

The '96 has the re-usable gasket.

You DO want to change the fluid......it can be a messy job.
I agree that any shop the "backflushes" or runs ANY cleaner through the transmission is a place to not use.
Reputable shops (including Ford Dealerships) use an "exchange" machine. This type of machine adds new fluid at the same rate and amount that the old fluid comes out. Dropping the pan will drain about 6 quarts of fluid. The remaining 6+ quarts are still in the rest of the transmission, cooler lines, and cooler. There is a LOT of fluid still in the torque converter. The system capacity is about 12.25 quarts......I run at least 15 quarts through to get MOST of the old fluid out.

This may solve your shudder and shift problems.
You should change the fluid at LEAST every 30K miles......21K miles for "severe" service.

First, let me correct my stupidity...this is a 1997...my bad. I dropped the pan and changed the filter. Then I added just over 6 quarts of Valvoline MaxLife ATF (Mercon Dexron III I think it said on the bottles...not Mercon V). My Haynes manual indicated I would only need ~4.5 quarts; however, based on the amount that drained out I knew that wouldn't be enough). The fluid is obviously much cleaner looking now. There was just a bit of metal sludge at the magnet (may 1/8 " accumualtion around its circumference). I also changed the filter. The filter seal was difficult to remove and I was careful not to scratch the hole it fits into as I pulled it out. It shifts much better on a quick 20 minute test drive.

Thanks!

One more thing. I'm planning on going 15-20k as is with the 50% change out and then performing a full flush. I did this as I feared an entire fluid change might shock the system. I think my fears are unwarranted though and perhaps the bad experiences people have had when changing out very old, possibly burned tranny fluid is more related to the non-reputable flush procedure you both mentioned earlier.

Ok one MORE thing...

I did notice that when still and holding the brake sometimes you hear a thud as the gear engages even after the 50% fluid change. This is not a new event and is more noticeable when going from drive to reverse. It is also more pronounced when staying at a standstill and never actually moving. Generally, if you back out of the garage then go to drive the shifting is not near as noticeable. It definitely is worse when just cycling through while holding the brake. Is that normal?

Thanks.

"Thuds" can be the result of many things ... the tranny certainly, ... but also loose/old suspension or sub-frame mounts ...etc, etc.

I would suggest you soon change (with the method you've already used) the tranny fluid again, perhaps not changing the filter this time, this will bring the level of "new" fluid up to approx 75%. And then follow the change frequency outlined in Haynes.

Also....The stuff you wiped off of the magnet...is normal wear. As long as it was a very fine stuff. If you had any "chunks"....that would not be good.

Keeping up on the fluid will be a good thing.

I also sometimes get a slight clunk going between drive and reverse (or vice versa)..... Some is normal as you are going from a stress on the drive train in one direction.....to the other direction.
Having had 1 transmission replaced...$$$$.....I am a bit sensitive to any sound that may be from anyplace near there.

Thanks to the both of you!