Hi Dave, It says in the workshop book to change every 5 years but i would advise every 2 years, thats about every 20k. I have changed my filter twice, the first time it took about 2 hours as the nuts and bolts where stiff has it had never been changed and i tried to change it while the pump and sedimentor unit was still connected to the car, its very hard to get the filter out of its casing, so the last time i did it i removed the hole unit, thats easy to do and makes the hole job very easy, took about an hour, you will need to remove the rear wheel and plastic cover under the wheel arch,
pete.