The Purolator air filters for my application are awful. The gaskets are way too thin.
I first bought a Purolator air filter in 2005 for my old Ranger. I didn't look at the filter until after I bought it. When I took it out of the box, I noticed right away that the gasket looked thin. I installed the filter just to check, and sure enough, the two halves of the filter housing were not even close to snug. The top half moved all over. I replaced it with an STP filter with a much thicker gasket.
When they came out with the PureONE oiled filter, I decided to give it a look...this time before paying. Sure enough, the gasket was still way too thin to seal properly.
I'm really disappointed with Purolator's air filters. It seems like a respected brand on BITOG, but even Fram got my truck's air filter right. It shouldn't be that hard for such a large filter company.