I never had issues with the PH8A. I tried the HP1 filters back in the 80's. I kept sucking the rubber flap in the filter into my oil pump. And that was just a stock pump with the long rotor kits. I went back to the PH8A and never had that happen again. When I was racing regularly, I would change the oil 2-4 times a month, so I went through a lot of filters. PH8A filters never let me down.