Purolator does not make Penzoil filters, Honeywell does. Honeywell also makes Fram. Most likely some glue used to bond the paper media to the cardboard end caps came loose and got lodged in the oil passage leading to the cylinder head. I have seen it a few times and all the engines had a Fram or other Honeywell filter on. I don't know how you sent the filter to Purolator to get tested when they didn't make it. For proof cut open a Penzoil and a Fram filter and compare them. Here and here is some more info on filters. If the engine ran fine before the oil change then the filter came apart or someone forgot to put oil in it before it was started. There is nothing rubber in the engine between the oil pump and heads. The only rubber is the gaskets on the chain tensioners but even if they failed the heads would still have enough oil pressure to prevent any damage because the tensioners are fed through a orifice that reduces the pressure to them.