I pulled out four brands of oil filters (in my stash) that fit my M35 and was surprised to see the differences in the hole configuration in the metal cores when you peer inside: AC Delco and Hastings had small diagonal slits. Union Sangyo and Mann (Purolator) had larger round holes. Does that mean two brands favor flow and two favor filtration? Wouldn't the AC Delco and Hastings be more prone to clogging with the smaller holes? Didn't Champion Laboratories have QC issues with some of their filters having poorly stamped inner cores? Opinions are welcomed.