[Tinker51]

It has been long enough ago now that I don't recall the exact details (That could me as early as what I had for breakfast, but I digress) but a member of a local club once did a semi scientific study. He bought various makes of comparable filters and cut them open to see what was inside. I don't recall all the data but the Fram filters were way at the bottom of the list and the Wix filters did very well. One of the interesting things he found was when the Fram filters were on sale for dirt cheap they were actually different internally then when they were not on sale. I have heard other people say on more than one occasion that all the various makes of filters are manufactureed by just a few companies and branded for whomever they are shipping to. Don't know if that is true or not. I use the FL1 in the SPF and Wix in everything else I have.