The stock oil filter for the second generation Ford Focus (2007-2011) is Motorcraft FL910S. This is the same size as the stock oil filter for a 2.3L SAAB 9-5. That means the same extended oil filter that is about an inch longer than the stock filter will also work on the Focus.
Before switching to a larger oil filter on your Focus, I do have one warning about the location of the oil filter. Because the oil filter sits straight up and down near the front of the car, adding an inch to the filter length opens you up for someday damaging the filter if you run over something. I haven't installed this larger filter and I didn't get under the car with a measuring tape, but it looks like the larger filter would hang almost as low as the front lip of the car. So do this mod at your own risk. The Focus won't go far if it's missing the oil filter because you ran over a log or something.
But don't use Motorcraft filters if you're going to go for a larger size because they shrank the size of the FL-400S a few years ago.
The stock oil filter part numbers for a 2.0L Ford Focus are:
The longer oil filters that will also fit are:
K&N HP 2009
Personally, I'm not going to use the bigger filters on my Focus. The risk of hitting the filter is too high in my view and the 2.0L Duratec 20 engines don't have the oil issues of the SAAB 9-5. But if you're looking for larger oil capacity or increased oil filtering, these long filters are available.
Current Automotive Sales and Coupon Codes:
$15 Off $40+ with code BIG15X at AdvanceAutoParts.com!! Offer ends 6/30
Take $10 off $30, $20 off $50 and $30 off $100 orders at AdvanceAutoParts.com with code A123 (exp. 6/30/12)
Save 15% Off Your AdvanceAutoParts.com purchase with code AAP15OFF (exp. 6/30/12)
Dads & Grads Special: Get 10% OFF on orders $99 or more! Coupon code: DADGRAD. Valid from 6/1 to 6/17.
Special Offers: Save on quality tires with these manufacturer's promotions available from Tire Rack.