Originally Posted By: roygage
Recommendations, instructions. "If you are working on a Gen4 V8 that is setting a P0521 or and low oil pressure indicated on the instrument panel in cold or hot weather and the engine is currently equipped with a PF48E oil filter, replace with a UPF48R if one is available."
"Note: Only use the UPF48R if if the Gen.4 V8 is setting a DTCP0521." And I will note this line is in red on the S.I.
Will someone please tell me, why would you only go with the improved filter if you had a problem? If the filter is the problem why no just supersede it to a improved version? Just seems nonsensical. And just what is the core problem here? Is the problem with the filters inability to flow oil or the filters bypass valve? Or, is the problem with the engines oiling system?
The "R" in UPF48R usually denotes a "racing" filter and probably has a higher bypass valve setting. It probably also flows better, as I believe their UPF filters are synthetic media (they use to be anyway).
It's pretty hard to imagine it's a filter problem. But you do mention in your original post that this engine sounds pretty dirty and is plugging up filters rather quickly. If the filter's bypass valve is under sized it could cause oil flow restriction if the filter gets really plugged up, even when the bypass valve is opened. Simply putting on a new filter and seeing if the oil pressure comes back to normal would say that the old (clogged?) filter is at fault. If a new filter doesn't restore oil pressure then the problem is not the filter.
As you mentioned above, definately use an accurate mechanical pressure gauge to verify the oil pump is heathy.