I too had lost 15 PSI on a Fram. Did not think much about it till I dropped all oil pressure at 6000 RPM going thru the traps and my Idiot light came on.
A fellow racer had a spare Wix 51515, Installed it and finished the night and drove home.
A few months later I changed oil and grabbed the last one off my shelf and installed it. In two weeks it too lost about 10 PSI. Pulled the first one out of the trash and cut it open. Found it was all smashed inside, cut the second one and it too was smashed just not as bad.
deeJAY ... 15lb loss would indicate to me ON THE SURFACE.... that the filter is actually FILTERING... instead of going on bypass
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Doc, I ran that PH8 for about 200 miles before that Test & Tune night. Engine sounded fine, just 10-15 PSI down from normal.
I had made 3 passes when I lost oil pressure and the Idiot light came on and I shut it off. This was a 383 in my 65 Barracuda. I run a tee fitting with a mechanical gauge and the idiot light sensor.
I go a tow back to the Pits and asked some of the Mopar and Ford racers if they had a spare filter. Ford racer had a few so I bought a Wix 51515 for what he wanted and made two more runs that night with no more pressure loss. I had bagged the Fram and tossed it in the corner of the garage and forgot about it.
When the second one caused a pressure drop I pulled it off and went with a Napa gold 1515 and had no pressure drop. This is when I cut the first Fram open. It looked like a beer can that was drank and crushed and folded in the center The pleats were all mushed up. But NO metal inside that I could see. I also cut the second one open and it too was damaged but not as bad.
The 383's oil pump ran 40 PSI at idle when hot and would go to 75 PSI above 2500 RPM. It was on the engine when I bought it. It was a HV pump with a stock pressure spring. It was still on the engine when I pulled that 383 and put a 318 in the car.
