[Stap Boy]

Oil Changes aren't what most would call "challenging" but... unless you are buying Oil in Bulk you don't end up saving all that much... coupled with the potential fookups you could do, it may not be worth the Moo-Lah. Even if it wasn't you that fookered it up (bad Oil Filter etc.. etc..) its hard to prove otherwise.

Plus you need to keep all your receipts and such just to prove you've done it should, heaven forbid, something happen to your lil Focus.

On top of all that you need to get rid of the old stuff, and down the storm-drain is a frowned upon method :)

BUT... its always a handy skill to have, makes you look more manly and such