I know that we have seen a lot of good ACDelco e-cores come through here recently. The addition of a real bypass valve is a huge improvement over the combo valve of the traditional e-cores. With this in mind, I decided to go back to ACDelco for my GM truck's oil filters. To some degree, the best filter for your car should be the one that is the OEM or OEM provided service filter. Obviously the PF48E is the OEM suggested service filter for this vehicle. In the past I ALWAYS used ACDelco filters (before they went e-core) So, despite being startled by its light weight as compared to the Mobil 1 M1-113 that I took off the vehicle, about two weeks ago I put the PF48E on the truck with complete confidence. Today, when I started the truck, I experienced more startup valve noise than I have ever heard before. It genuinely worried me that something might go snap. I just can't explain how off-putting it was. So, I don't know what the deal is. I cut the filter open and it looks fine. Maybe ADBV not worth a darn or a for some reason stuck bypass valve? All I know is this, filter came off about 30 minutes later and was replaced with a Mobil M1-113, which is also a direct cross to the ACDelco UPF48R. I guess I'm done with that experiment. It's a shame, in my mind a GM car is supposed to have a blue can under it. I might use the CARQUEST 86040 in the future if I can get past the hangup of too few center holes. It's about half the price of the Mobil 1 filter and looks every bit as good. I was really impressed with it (see cutaway). Either way, I don't care how good they're looking or what improvements have occurred, the e-core just isn't ready for prime time yet. It's just too minimally engineered. I'm done with it for good.