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I've got a '92 GM 3800 with 175k miles on it. I don't think the transmission fluid has ever been changed. I'm about to take a trip with it, and was wondering if I should swap in some fresh fluid?

There is so much debate, with some saying this will ruin the transmission, and others saying it won't. I'm not talking about a full flush, I would just use a siphon and pull out some of the old fluid, and replace with new.

I worry about the old fluid being able to handle the heat and stress of the 8 hour trip.

Thanks.

What I would do is drop the pan, let whatever will drain, drain, and put in a new filter. Clean the pan and magnet while it's off.

There might be proof out there why a flush can kill a tranny. But it's mostly a disturbing trend where high mile trannys die soon after a flush. Knocking stuff loose, removing gunk that was holding things in place, etc...

Wikoff is right, and if you are still a little worried, buy a bottle of lucas trans fix. it's really thick and many here have had great results with it in high mileage transmissions, including those that were poorly maintained.

The procedure for dropping the pan, changing the filter and replacing about half the fluid is described here in a Techinfo article.

I have come to the conclusion that if the flush kills it, it was bound to happen soon anyway, and was only being held together by the crap you just flushed out. With that being said, I just had a pan drop and filter change on mine, and it still seems to be happy.

Well, there's no reason to spend the extra money just to speed up the failure.

Pan drop, filter change, and new high-mileage ATF fluid. Castrol High Mileage is extremely thick fluid, and is on sale at Pep Boys right now...

zirconx wrote:I've got a '92 GM 3800 with 175k miles on it. I worry about the old fluid being able to handle the heat and stress of the 8 hour trip.

What color is the fluid now? Pink? Clear. Brown but clear? Brown and cloudy?

Since that had Dexron II or Dexron II E or Dexron III as the original fluid, I 'd be careful to buy replacement fluid that was the most like the original. I would not put in the Dexron VI, even if it's listed as acceptable.

If it's clear or brown, my own opinion would be drop pan, replace filter, and put in the 6-7 quarts of Dexron III. The fresh detergent in the new fluid will start to pick up any deposits. I would not add any additives. Let the detergents do their job, slowly, hoping not to cause any particles to come loose, if there are any.