[quote name='Simon S' post='16034' date='Mar 22 2009, 12:18 PM']I have just replaced the accessory belt on my tdci Focus and noticed the oil filter looks like it has not been changed in ages. As Ford mechanics would never consider not changing the filter

I was wondering how often they are supposed to be replaced?
Shall I give the engine a flush do you think?[/quote]
the oil filter should be changed every time the oil is changed.
i wouldnt bother using any flushing agents, just run the engine until the oil is nice and warm and let it all drain out. i usually leave my car an hour or so to let all the crap drip out of the sump.