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Doug, ASE Certified Technician
Category: Car
Satisfied Customers: 8609
Experience:  16 years automotive and OTR repair including specialized training from Toyota and Mitsubishi
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how to change the auto transmission fluid

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how to change the auto transmission fluid

It is rather typical to only see around 3 litres from a plug drain on the transmission. This is because the pan is simply the reserve fluid and the rest of the fluid does not freely circulate with the pump not turning (engine not running).

The best route to replace all of the fluid is to use a flush machine. These hook up in-line with the cooler hoses and simply exchange the old fluid with new as it is pumped through. This is really the only way to be sure to get "all" of the fluid out.

You can remove a little more fluid if you drop the oil pan and pull the oil filter out. It retains another litre or 2 tops.

The official Mitsubishi procedure to change all of the fluid in absence of a flush machine is to remove one of the cooler lines and run the engine to pump the fluid out, then remove the drain plug to drain the pan. Add new fluid to the pan and then run the engine again to pump out the fluid, then shut it off and refill entirely.

I am attaching the service manual instructions for changing below (note that the fluid amounts are an average, it will vary based on 2WD vs 4WD, size of your cooler, etc).
Customer: replied 4 years ago.

thanks doug for this answer, could you please send the illustration that shows the connection of the hoses to the cooler

thanks paul


You're welcome Paul.

The cooler lines are on the right side of the transmission using banjo bolts (round fitting on end of the line with a bolt holding it to the transmission. It is a much better option to go to the cooler however as not only will you get the fluid out of the cooler lines this way, it is also much easier to access.

The cooler on a 2008 should be in front of the radiator behind the grill. The hoses going to it just have spring clamps holding them on, so you can squeeze the clamp and slide it back then pull the hose off. You would then want to use some scrap hose to extend from the cooler to a bucket and to extend the removed hose into the bucket. This way both lines will drain into the bucket without getting all over your bumper etc.

The older models ran the cooler inside the radiator, so there would be two ports on the bottom of the radiator to access the lines. Again on your 2008 you should have the auxiliary one though. The auxiliary cooler will look like this (sorry for the schematic picture, I don't have a good photo of 06+ models):
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