I just purchased a used 2003 Ranger with a 4.0 SOHC. While doing the first oil change I was surprised that the filter I removed a Peformax PO-173, is much smaller than the ph2 I bought as a replacement. the threads match, but it appears the mount fits the smaller filter rather than the PH2. WTH is going on with this? Help, this what I am drivin to work tomorrow.

 

Looking up the Performax filter shows it fits that engine, it's just narrower.

I say scrap both the Fram and Performax filters and pick up a Motorcraft FL-820-S. You can get them at WalMart for about $5 and they are factory spec so you know it will be the correct filter.

Here's a pic I found that shows them side by side. The threads and seal look the same, the Motorcraft housing is a little wider though.
F150008.jpg Photo by sixshootertexan | Photobucket

 

stick with the motorcraft filters , they contain way more filter media

forgot to mention that WIX filters are a damn good filter as well

smaller diameter oil filters only aid in increasing oil pressure

 

Makes sense. Thanks for your responses. All these years I have been guilty of assuming that oil filters were all pretty much the same, that it was the oil that mattered. Perhaps it is time to change my thinking on that.