If you scroll through the pages you will find the answer that you are looking for. This is a very common question as you will find out. 60000 miles to save u some time................ or if the belt is soiled/contaminated with oil or any fluid.
Mind you dive75 it varies depending on the vehicle. Thats probably why the question has been asked so many times as people are enquiring about different vehicles. 60000 miles is a general rule of thumb - its best if you contact a Mitsubishi reapir agent to find out the exact interval or else you could be looking at big repair bill.