And neither do I, but a PH-63 is a AC delco filter and while I am only exposed to current auto news, it does seem like Pennzoil has a better product, even if only marginal. As far as oil filters, I really don't think GM would produce a product like a oil filter that they were going to try to pinch a few pennies, so I am a creature of habit, and even since I was in a Navy CB unit, the mechanics always stuck by their statement, "You can never have too fresh of oil in the engine!" I don't knock down all that many miles on my Tahoe, so in that sense I'm even worse on the oil than say a heavy used driver. I should say that Mobil-1 is still a 'Dexos oil' so GM thinks it's ok, but . . . ? I do wonder about is the Viscosity oil have. Is a 0W/20 oil really necessary ? At 210 degrees or hotter all that good on a super hot summer drive?, is that 20W really all that good or is maybe somethings else better ? Got me guessing ! Oil pressure is the result of the volume of oil the pump puts out. Every rebuilder ( Jasper, powerstroke ect) installs a high volume oil pump as standard policy. I assume GM went with a high volume oil pump for the same reasons, and as a result of the lighter weight oils like the 0W/20 oil.