3rd Gen Montero Transmission Service Advice

[tadeon]

I have a 2006 Montero Limited with 175,000 miles, but I’m not sure when the transmission was last serviced. I’m considering a drain and refill with Mitsubishi SPIII ATF, but I’ve heard mixed advice—some say there’s a risk of transmission failure after a fluid change with high mileage. Currently, the fluid still looks pinkish-red and doesn’t smell burnt, and I haven’t noticed any shifting issues or shuddering. I’ve watched videos where some people advise against changing it, while others say it’s fine. I want to keep up with maintenance but feel hesitant about this one. Any thoughts, suggestions, or personal experiences, good or bad?

 

[alanymarce]

I can't imagine any reason why it would be a bad idea to replace experienced ATF with new ATF (provided it's the right spec of course). I'm interested in seeing any reasons why it would not be a good idea.

 

[Inyo_man]

Complete a full fluid exchange with SP3. The procedure is relatively simple. Drain and refill the pan.
Remove the ATF line that feeds the cooler. Cycle the ignition (briefly) so some fluid is pumped out of the line. Replace through the dipstick. Continue brief cycling of ignition until fresh fluid is being pumped out. You'll need about 12 quarts of fluid to do a complete flush. Remember to check the level with the engine at temp., after cycling it through all the gears, then check while running in N.

These transmissions are bullet-proof, if taken care of properly.

I used this mob linked below as a supplier:

Mitsubishi ATF SP III Automatic Transmission Fluid (MZ320200)

Genuine OEM Mitsubishi SP 3 automatic transmission fluid. This ATF is recommended for the 1G/2G DSM automatic transmissions, Evo 8/9 ACD pump, the Evo X AYC and Evo 4/5/6 AYC.

stmtuned.com

Cheers

 

[tadeon]

I just completed a drain and fill, draining about 6 quarts from the pan and refilling with SP3 ATF. The transmission shifts smoothly with no issues. I’m planning to do another drain and fill in 10-15k miles.

 

[Michael Brown]

I don't know of any downside to not doing a fluid replacement on these vehicles provided you use the correct fluid and follow the procedure to set the level correctly.

If the fluid was still red in color, it was probably fine. The fluid should be good for 50k miles or much more depending on driving. If you experience shuddering or shift issues, that is likely the sign to change it.

 

[EpicPlanet]

I have heard something like this too - don't change the trans fluid on high mileage vehicles unless it has regularly been changed all its life. Something to do with new fluid exerting higher pressure on some of the components. However, I changed it on a 1991 5.0 Mustang that had, I think, around 150k miles and had never been changed. No adverse effects.

Also changed it on a 2002 Diamante VR-X with over 200k miles. Extremely dark. No records or evidence of it ever having been changed. Continued running with no issues.

However, I have seen other people do this and have transmission failure a few thousand miles later.

 

[Michael Brown]

Usually the transmission failures are due to using an incompatible fluid. Some advertise as working for all makes/models, but this isn't true. Incorrect fluids have different additives that may degrade or destroy certain alloys like brass that are being used as bearing material.

I've really only known changing with correct fluid to sometimes be a problem in old transmissions with band style engagement.