After changing my oil I noticed that at startup I was hearing lower engine knocking sounds for a few seconds. This happened at every startup and sometimes even at idle. I had just switched to Purolator Pure1 from the Motorcraft FL1-a. I bought a new Motorcraft and took off the purolator. NO oil spilled out when I unscrewed the filter. The anti-drainback valve had failed! Put in the Motorcraft and noises went away. I am aware that Purolator makes the Motorcraft filter but I thought this was interesting. Guess I'll stick with the Motorcraft.

I have seen in several places that the drainback valve on the PureOne filter does not meet Ford Specs because it's at the wrong end of the filter. Where as the Motorcraft (PureOne filtering media) has the drainback valve in the proper place, thus it's an approved design.

Since you are getting the same filtering media with both filters I just stick with the good ole' Motorcraft FL1A.

The drainback valves are in the same place. Its the bypass that is in a different location. Top of the filter in the Motorcraft, bottom in the Pure1. But yes, I will stick with good ole' Motorcraft also.