I'm certainly not an
oil/
oil filter expert,so I'll just state my real world expeirences................
Sometime ago, there was a similar thread and the Fram filter was supposed to be junk, they touted the AC Delco filter as one of the best....So, being a little worried, cause I use only Fram filters from Wal Mart in all my stuff, I went out and bought some AC Delco filters...
Here's what I found: In my Toyota company car which at the time had about 300,000 miles on it and nothing but Rotella T 15/40
oil and a Fram filter in it from it's first oil change since new......when I changed my oil at the next interval I used the same oil and then the AC Delco filter and the next morning on startup, the motor "knocked" for at least 10 seconds, I revved it to maybe 1500 rpms and it went away, after that it was o-k.... after sitting overninght it did the same thing for three days in a row, so I took off the the Delco and put a new Fram filter on, never has done it since....The car will hit 400,000 miles in a few months and the only thing done on the engine was to change the valve cover gasket..... That's the third company car with over 250,000 miles with Fram filters and Rotella oil and none have ever had the engines worked on, so I guess I'll keep using those cheap, no-good Frams from Wal Mart.......
On my race car I use the Fram HP series filter and cut them open to check them out and the motor at the oil changes, never seen anything unusual or anything to make me switch brands.......
Nothing scientific here, just my real world results..........
David