PF46 Vs. UPF44
Melting Slicks
Joined: Jan 2006
Posts: 3,003
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From: Life ain't no dress rehearsal, are you gonna wait to get your toys til AFTER you have a heart attack?
In addition, I believe that there is something about a bypass valve in the filter vs. a bypass valve in the engine but I am not sure which is which. 44 vs. 46.
Race Director
Joined: May 2001
Posts: 15,324
Likes: 2,080
From: Guelph, Ontario
Neither of those filters have a bypass valve (also known as pressure relief valve) in them, as the engines that these filters go on have them built into the oil filter base on the engine block. In 2007 they changed things on the LS2, so the bypass valve needs to be in the oil filter now, that's why they changed to the PF48 oil filter. The UPF44 and PF46 filters will not fit the 07-08s (or the 06-08 LS7)
