Transmission fluid change
 

1996 850 Turbo Wagen with 64000 miles and origional transmission fluid. Fluid is brown and smells a little burnt. Trans shifts a little hard sometimes. Should I do a drain snd fill per the Haynes manual, or a more gradual drain and fill over 3 or 4 times that some recommend? What fluid would you use?

Thanks, that's what i'll do!

Wait, I see that is full synthetic. Is that safe to mix/replace with the origional dino fluid?

Drain and fill will only replace some of it, so sometimes people will drain and fill several times to get more new fluid in there.

google around on option b, which is to disconnect the transmission cooler lines. (this is the shop method btw) At one point FCP actually sold a kit with hoses and buckets but the idea is to use the transmission (engine running) to pump the fluid through a clear hose into a bucket while it fills from a bucket with clean fluid. when the output is translucent you are done. Similarly the S40 service manual suggests a process where you disconnect the cooler line and pump out 2 quarts, stop the engine, refill from the top, restart (rinse/repeat until good).

method revision (suggestion)
 

The efficiency of letting the transmission pump out its own dirty fluid is obvious. The trouble with drawing in fluid through a bucket of new fluid is one of control.

I think it's better to pump out 2 quarts at a time, stopping the engine, refilling 2 quarts of new fluid and redoing the process.

So I am using one of the popular methods promoted by Robert the utube 850 guy. I drained the xmission as much as would come out = 3 qts. Then added 3 quarts and drove around 100 miles. Repeated the process and will do at least 3 times total. After a few hundred miles I will probably do the complete flush. Shifts very smoothly now!

I'm with MT6127. I used some left over clear (green tint) hose from a water softener that fit my trans hose nice and tight. Ran it over the drvs fender into a jug.
I have 300K and my fluid was nasty. I started the car and let it idle and pump fluid out into a graduated 5qt oil container while I shifted through each gear and watched the hose. When I started to see bubbles I'd shut off the engine, read the measure of the fluid pumped out and drain it into another container, add that amount of fluid or a bit more and than do it again. I did it four times so I knew I had the best flush I could do and the trans has held up just fine for a few years now.
Last addition I was more careful about not overfilling. I took it out for a drive each time and shifted through the gears a couple times manually to get it to the full mark. It's really hard to get it right at full.

You will spend more time trying to unhook and reconnect those transmission lines. Do a total drain, then refill the same quantity that you drained. Run the transmission for 3-4 minutes, then drain/refill again.

Done.

I found that when ever I disconnected the trans cooler lines I had to replace the seals. I would not try to reuse the seals and that goes for the locking clips that hold the hoses to the cooler. I had one blow off while driving, not good for the tranny - see my post on installing a new transmission.

I agree Phil. I went to the dealer and picked up new O rings and clips. It wasn't hard getting it apart or putting it back together. Just needed to pull the one hose. Very happy with the results.

I went to the dealer before I replaced my radiator and they wanted over $100 for O rings, seals and clips for the trans cooler and oil cooler hoses. IPD was less than $50 for all of it.