Bought an Repo'd Evo X a while back. Has about 170,000 km (105,000 miles). Don't have the past records on the car. Thinking about changing the majority of the fluids just to be safe. Wondering which ones are essential and an approximate cost of each (most will be done @ dealership). Thank you

 

T-case, rear diff and transmission. You can always call the dealer to get a quote.

 

All of them. Especially at 170k kilometers.

 

If it's an MR/SST, pepper your angus. Otherwise it's not terrible. Not sure what Mitsubishi UK charges but I've see people having been quoted $1200-1700 USD by the dealer for all fluids on an MR. You're looking at about 1/4 of that to DIY.

 

I've done all fluids myself. It's not too bad to learn.
Oil change fluid and filter obviously
Transmission (and if it's an MR there's also a filter to change)
"Active Center Differential"= a locking center diff aka transfer case + a limited slip helical-type front diff together in one unit. You only need to change the "Gear Oil" for the locking diff part.
"Active Yaw Control" Diff= rear differential that has two components. One is a typical clutch-type limited slip differential that you'll see in many sports cars. The other component is two clutch packs that can vector torque to either the left or right wheel. Both components have fluids to change (different fluids), which are simple drain and fills. Dont listen to mechanics that are confused with the complexity of the EVO's drivetrain. There are two fluids, drain and fill. The rear differential part is gear oil, just like the center diff. The "yaw control" clutch part uses automatic transmission fluid.

The center diff "ACD" and the rear diff "AYC" take some time to explain, so I'd Google search if you want a more elaborate explanation (or maybe you know most or all of this).