Q: Does the AYC fluid have to be changed at a Mitsubishi Dealer? A: According to the current service schedules for the Evo 4 onwards, the AYC fluid for the AYC clutch packs (ATFSP-III is now used as AYC fluid is no longer available) and the ATF fluid in the boot reservoir has to be changed every 4,500 miles (it has been suggested that Mitsubishi may extend this service interval for the AYC to 18,000 miles at a later date). Changing the AYC fluid in itself is not a problem. The problem comes when you change the ATF fluid in the hydraulic actuator system as you have to bleed the air out. The workshop manuals do state that the hydraulic system can be bled manually but it has been found that it can be difficult to get all of the air from the system using the manual method. The easiest way is to use the Mitsubishi MUT-II diagnostic tool, which is an electronic control box that plugs into the car for fault finding and servicing. The MUT-II has a program that operates the valves in the hydraulic system in the correct sequence so the air can be bled completely. Unfortunately the MUT-II is only available at Mitsubishi dealers or selected approved agents. Back to question page