The next time I do an oil change on my almost stock BBC I'd like to maybe try a different oil filter. I've been using the Fram PH5 with no issues. However, I have enough room to fit a taller filter like a Fram HP4. The PH5 is 5.170" tall and the HP4 is 5.75" tall. I figure that the taller filter would allow for a little more capacity and that is always welcome since my motor uses a stock truck oil pan. I was comparing the stats on the both filters mentioned above and I found that the PH5 does not have a filter bypass relief valve as where the HP4 uses one. Also, Fram states that the relief valve on the PH5 opens at 8-10psi as to where the relief valve on the HP4 opens at 22psi. I'm a little confused on that last piece of info. Why would Fram say that the PH5 doesn't use a pressure relief valve and then say that it opens at 8-10 psi? I'm figuring that someone on this forum knows enough about oil filters to tell me what it is that I should be running.