C5 Oil Filter Confusion

[Bob S.]

My understanding is the C5 LS1 engines have an engine oil filter bypass valve in the block (Part # 12684294). Did the original manual specified PF-46 oil filter also have a bypass valve? If so, is it redundant to the engine BPV? If not, is it okay to run the current PF46E filter that has a BPV in it? Did the PF46 have an anti-drainback valve? Micron Rating?

The original PF46 was replaced by a PF46E (19210283) which in turn has now been replaced by PF46E (12737094). Per the acdelco parts catalog, the 19210283 has a nylon poppet style bypass valve and a Filter bypass setting for today's high flow GM engines. No mention of an anti-drainback valve or the micron ratings. Catalog does not yet show the newer 12737094, however a parts supplier shows a running design change Aug 2024 – May 2025 with a revised high flow threaded plate design and a change in the filter bypass valve from the prior 150kPA to 100kPA that clearly by the picture is the 12737094. Does the 127… have an Anti-drainback valve? Micron Rating? Issues with a redundant bypass valve at the lower setting?
I submitted a question on the anti-drainback valve on the PF46E filters to GMPARTS.com and got back "There is no mention in the catalog or other information we have access to of the requirement of an anti-drainback valve."
Information/Recommendations?

[Joe L.]

My understanding is the C5 LS1 engines have an engine oil filter bypass valve in the block (Part # 12684294). Did the original manual specified PF-46 oil filter also have a bypass valve? If so, is it redundant to the engine BPV? If not, is it okay to run the current PF46E filter that has a BPV in it? Did the PF46 have an anti-drainback valve? Micron Rating?

The original PF46 was replaced by a PF46E (19210283) which in turn has now been replaced by PF46E (12737094). Per the acdelco parts catalog, the 19210283 has a nylon poppet style bypass valve and a Filter bypass setting for today's high flow GM engines. No mention of an anti-drainback valve or the micron ratings. Catalog does not yet show the newer 12737094, however a parts supplier shows a running design change Aug 2024 – May 2025 with a revised high flow threaded plate design and a change in the filter bypass valve from the prior 150kPA to 100kPA that clearly by the picture is the 12737094. Does the 127… have an Anti-drainback valve? Micron Rating? Issues with a redundant bypass valve at the lower setting?
I submitted a question on the anti-drainback valve on the PF46E filters to GMPARTS.com and got back "There is no mention in the catalog or other information we have access to of the requirement of an anti-drainback valve."
Information/Recommendations?

Bob------


The PF-46E will SERVICE your LS1 perfectly. According to GM, it has no bypass valve but does have an anti-drainback valve. The bypass valve is not necessary for an LS1 as it has an internal bypass valve. So, whether the original PF-46 had a bypass valve is a moot point as far as an LS1 is concerned. I do not think that the original PF-46 had an anti-drainback valve but the PF-46E does have an anti-drainback valve. It makes no difference either way because the anti-drainback valve is superfluous for an LS1 application where it is installed with the mounting plate facing up.

The primary difference that I have observed with the "E" suffix oil filters (of which there are now many in the ACDelco line replacing non "E" suffix filters) is that they have a threaded insert in the mounting plate whereas non "E" suffix filters have the threads tapped directly into the mounting plate.

By the way, if I were you I would switch to the UPF-46R filter. This filter will SERVICE your application perfectly and utilizes a synthetic media filter with considerably better filtering performance. I use UPF series filters in all of my vehicles.