There is a good diagram of oil flow on the first page of this pdf. Depicts both dome-ended and gasket-ended bypass valves.

http://www.bullittarchive.com/5000/5003/Oil_Filter_Cut-Away_Comparison_Kit.pdf

"Aftermarket filter media is not designed to meet Ford's requirements and the media area is typically smaller" "Internal pressure relief valve at inlet" quote from Ford

Is there any other filter manufactured like the FL820-S? Even Purolator, the outsourcing manufacturer, Does not make their branded filters for this application like the MotorCraft.

I would like greater efficiency even if I have to change the filter sooner but it seems there is no better design than OEM at any price for the Modular V8's.

Can anyone refute this logic?

Jesse East
Owner/Technician
East Garage
Roanoke, Virginia, USA