Change it. Leaving it in just postpones the inevitable and will just make matters worse.

When you change it, find a decent lube place and have it "flushed" and not just drained and refilled. Draining it will only get what's in the tranny and not what's in the Torque Converter. Flushing will get all of the fluid out Make sure they use 100% compatible fluid or you will toast her tranny. If you're not 100% sure they will use the right stuff, buy the mitsu fluid yourself and bring it to them. Worth the extra cost.

 

This was what I have been concerned about, on the Grand Am forums they all say that if you "flush" at high milage vs. a fluid "change" the pressure of the flush process can disrupt the seals and rings internally and cause problems too.

Although the Montero Sport is a bit differant. Since the fluid calls for a "Mitsubishi" fluid not a more universal fluid, if you "change" with Mits fluid and that is not what is in there currrentlyyou run the risk of mixing [:'(]...so the "flush" would be best.

This is something I have yet to decide on, let me know what you decide to do!

 

I don't understand your logic Carlover. If it had the wrong fluid it would not run right. Besides, there is nothing wrong with mixing proper fluids.

Don't Mitsu Sports have a drain plug on the tranny pan, just like on the regular Montero's? If so, just drain the few quarts that come out of the pan and top up with Mitsu fluid. That should not "shock" your tranny too much, and is simple to do. It will benefit your tranny by removing some of that "spent" old fluid.

I am also beginning to think that this whole "you gotta have genuine Mitsu fluid or the car will explode is a bunch of hogwash". If you put a Dexron III clone in your "newer" Mitsu, your tranny will fail. However, ATF +4, or any of the "Universal" ATF fluids should be fine.

 

Do you know how to spell assume? It makes and *** out of you and me

All I am saying is that I have a hard enough time figuring what has been done to MY Montero, let alone his. I don't know if the fluid has ever been changed either, but if it has and the fluid isn't the EXACT same as what is put in during the "change" then you are mixing.

Sorry to drag out the issue, but all I have read in the Montero forums is "Use Mitsubishi fluid!", I don't know much about mixing a universal fluid with a mitsubishi fluid, that is all I am saying.
I love the change logic vs. the flush,I just don't want to do any harm in the process by mixing.

 

LOL, I don't think you should compare a GM Grand Am (GM stands for Great Mistake right?) tranny to a Mitsu tranny.

Seriously, the Mitsu automatic tranny in our Gen I, Gen II, and Sports are some of the most reliable tranny systems I've seen. I obviously can't say with absolute certainty that you won't encounter an issue but I can say that I've been involved with a group that wheels mitsu's for the past 5-6 years now having taken them through some of the harshest trails (Dusy-Ersham, Fordyce, Rubicon, Isham Canyon, top 10 hardest trails in Moab, etc.) and have yet to hear of someone's unit failing. Including folks that don't take care of their mitsu's who ask our club for help w/ Mitsu 4x4 problems, I can only recall 1 or 2 AT's going bad and in both cases, it was due to some bozo putting in the wrong fluid. Of course that's not to say it won't need a rebuild a some point (300K Miles?). Lets face it parts wear out no matter how well lubricated they are.

My own 1990 has over 250K miles (bought it w/ 60K) on it's original tranny and I've wheeled the heck out of it putting far harsher strain on it than most would ever do and again, no tranny issues. I also neglected to service (drain & refill it) or flush it for the first 3 years of wheeling and only recently (180K) have begun to flush it regularly each year due to it's age/mileage.

Again, these are my own personal experiences so your mileage may vary but I suspect your tranny will be fine with a flush.

HTH.

 

Dont believe the hype - go ahead and flush. If something was to dislodge and cause problems, you would already be having drivability problems. I would not be suprised if your tranny is smoother shifting cause it actually has fluid with the right viscosity as Mitsu intended!

 

[sm=thanx.gif]

I understand where you are coming from, and your encouraging words are nice to hear from me a new Montero owner and I hope the thread starter as well.

I know what I will be doing when I have the money.

 

Gen I and Gen II Montero transmissions were made by Aisen.

Gen III Montero transmissions made by Mitsubishi.

Montero Sport transmissions made by Mitsubishi. (I think)

I don't think we really know about the reliability of the Mitsu trannys yet.

The old talk about "flushing transmissions might cause them to fail" has been debated over and over on many internet forums. I personally flush my fluid, or do partial changes regularly so I do not have to worry about it. One thing everyone agrees on. Regular flushes will help your transmission last longer. If I purchased an older car with unknown history, I would do a partial flush.

Carlover, there still is no problem with mixing a universal fluid with genuine Mitsu fluid. Or Mitsu fluid with universal fluid. Or Mitsu fluid with Amsoil. And on and on....

 

That would be a bunch of BS. I run non-mitsu fluid in my Tranny. Other fluids work fine as long as you know for sure they're 100% compatible. Personally, I'd get a letter from the manufacturer that it will work with your year/model vehicle/transmission.

For example Mobil 1 says on the bottle that it will work in Mitsu transmissions. They just don't tell you it doesn't work in all of them especially those in a Gen I Montero. Not sure about the Gen II or Gen III's or the Sports.