I buddy of mine told me years ago never to do it on a high mileage tranny. I found this while surfing which is basically what he told me.

http://www.trustmymechanic.com/transslip.html

Please understand that I do not have a huge knowledge of trannys. My buddy is 20 years older than I am and knows his stuff. I had an old blazer that the tranny was slipping in so I did the fluid and filter change. When I was done it wouldn't even move. <img src="/forums/images/graemlins/evil.gif" alt="" /> I am by no means being a know it all but am trying to just help out. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Ok, After looking at an actual flush and fill, it does take out the old and put in new. I'm not sure what it is called he had done then?? It involved pumping the old fluid out and though a series of filters and pumping it back in. I saw them doing it and am positive thats what they did. What is it called???? But anyway it didnt help. It actually made it worse.

EDIT- After watching a video on how the flush worked I think I figured out what I saw. The old fluid was going into the machine, well I thought I saw it coming back out. What I think I actually saw was the new fluid going in. That explains why it got worse though. Sorry for throwing you guys off. I definately learned something new. I could have sworn the guy told me it was just filtering the old fluid though??? It still may have been??? Its getting late.... <img src="/forums/images/graemlins/sleeping.gif" alt="" />

Les, all my previous trucks (cept brief stint with BIII) were sticks, so this is my first regular DD with a slush box... I wasn't sure the change interval on mine when I got it, and wanted to put it to some heavy towing use... rather than pulling the pan, and getting all crazy, I simply did a little at a time. For my last three oil changes (May through to now) I've drained 4-5L of trans fluid each time, through the drain plug (the rest sits in the TC). Should be theoretically all new fluid by now, but I'm gonna do one more partial with my next oil change, just to be sure. The magic box seems to shift a little crisper now, and is smoother from a stop.

Heat is the enemy of any auto (so they tell me), and if your fluid is breaking down, then it can't dissipate heat as quickly, can it? I say change it a little at a time, and get another 172k miles out of it.

(should be taken with a grain of salt, since I'm still trying to figure out what "PRNDL" stands for. <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/drunk.gif" alt="" />)

I change my fluids each year. I changed it in the SR when I purchased it (200k) no problems yet.

Realize your buddy who said not to change it may be basing his knowledge on his experience which may be in specific tranny models/brands.

I say change/flush it Les. Mitsu auto's are pretty rock solid so long as the fluid is good. Burnt old fluid isn't good.

I followed the 'don't change fluid in an old tranny' philosophy on my truck until a valve (or something) got stuck meaning it would not downshift properly. Felt like there was no power after a stop (Scottie had the same issue once with his '97 LS). It re-set itself after ignition off, but that was enough to convince me.

I immediately dropped the pan, replaced the filter, topped it off and added some trans tune. I then drove it straight to the dealer (10 miles) for a full fluid flush. I've had no issues since. Tranny is smoother and I have piece of mind. The flush was something like $170 including fluid. When you think about the cost of Mitsu tranny fluid per quart, I thought it was a great deal <img src="/forums/images/graemlins/kewl.gif" alt="" />

I have heard that these trannys are very robust, unlike some others <img src="/forums/images/graemlins/smile.gif" alt="" />

I always change the fluid in my Raider. Pull the pan, change the filter. Wipe gunk out of the pan. I also go as far as buying the line cleaner (its in a green and gray aerosol can) and it flushes all the old fluid out of your trans cooler. Top up the transmission with ATF+4 or Diamond ATF. When I did it my first time on the Raider I changed the fluid again after the 2nd oil change. <img src="/forums/images/graemlins/kewl.gif" alt="" />

I think the old fluid in a high mileage tranny is a domestic car thing, our Aisin transmissions are a different kind of monster. I have 170k on mine and it was flush and filled with Diamond sp-4, my other one has 130k and had probably never been changed until i owned it and i did the same flush and fill with the mitsu trans fluid. Both are solid and have no problems, it won't hurt to have clean fluid. Aisin transmissions like clean fluid it keeps the hydraulic valves clean. LT learned this in his 89 recently, his filter clogged and his tranmission would boil over after driving it a few miles. He put in a new filter and fluid and it was good to go.

I'm glad other people are answering this question now. <img src="/forums/images/graemlins/smile.gif" alt="" /> I was answering the question based on my experience. And yes, you are right. All the problems I had were on domestic cars. <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> Sorry guys, I'll go back to my corner now..... <img src="/forums/images/graemlins/lol.gif" alt="" />

Now that i'm thinking about it, I do have sluggish shifts in the morning. I thought it was just a cold issue.

I just bought new tires so I either need to hold off on the flush or try the Phil method of replacing a bit at a time.

Where do you find this Diamond ATF elixar <img src="/forums/images/graemlins/lol.gif" alt="" /> Dealer only or can I find it online?

Les, I may be making a dealer run to Salinas today when we go to Gilroy. If you need something let me know.