transmision fluid

michael schulte · Post by **michael schulte** » 27 May 2010, 09:37

have 97 850r. 140,000 miles. transmision fluid has been changed twice using dino trans fluid. I would like to switch to synthetic. the repair shop I go to has a machine that pumps out old trans fluid at 3psi while putting synthetic fluid back in. I was wondering if anyone out there has had this done or would offer their opinion as to which fluid is best at this time.

Post by **FlyingVolvo** » 27 May 2010, 10:17

I would be careful using those machines, as sometimes they can cause issues in the transmission. The better method would be to do a series of drain and re-fills. Simply open the plug, and it will drain about 3.5 quarts. Refill with the same amount, and drive for a while, then repeat 2 or 3 more times.

I did this going from rather dark and nasty conventional ATF to Mobil 1 Synthetic ATF and had no issues. I've done a total of 5 or 6 refills now, so all the old stuff is basically gone. There are also a few write-ups here about how to do a flush yourself by pumping out the fluid by the transmissions own power, instead of a machine forcing it in.

I highly recommend Mobil 1 Synthetic ATF. Or if you have cash to burn, Amsoil Universal ATF is great stuff.

Post by **polskamafia mjl** » 27 May 2010, 12:11

DON'T POWER FLUSH THE TRANSMISSION!

Seriously though, it may work out for some people but the risk is not worth taking. ecbsykes is 100% right about doing the drain and fill method instead. I'll post the link at the end of this post. The power flush can and often times will flush out the gunk that is holding the seals together and it forces that gunk throughout the transmission. Do the drain and fills and use Mobile 1 synthetic as ecbsykes suggested.

Drain & Fill -> https://www.matthewsvolvosite.com/forums ... php?t=8767

A long discussion about the drain & fill -> https://www.matthewsvolvosite.com/forums ... f=1&t=8742

Good luck.

Post by **jblackburn** » 27 May 2010, 12:19

If I were switching entirely from Dex-III to Mobil, I would completely flush it.

Drain and fill would work OK if you're using the same fluid. If your fluid is dirty, then I would do a couple drain and fills with regular Dex III ATF, let it run through the car for a couple months until THAT is clear, and THEN switch to the synthetic.

That's how I did it, anyway, and it worked fine for me.

When it came time to switch, I drained the pan, then ran Mobil fluid through until it came out clear red. Around 12 qts or so. Expensive, yeah, but you won't have to change it again (hopefully) for a while.

The transmission has its own pump; look up the "modified flush method" here to do that. Flush machines are bad.