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Does anyone know what is new with the PF454? This filter apparently replaces the PF25 which has been in use since about 1968 (small and big blocks). Are the changes the same as the PF1218 which I think is a check valved version of the PF35? Is there more to this change?
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Tony -
Re: Oil Filters PF454 Replaces PF25
I have a PF 454 installed on my Cosworth Vega as its internal drainback check valve will prevent drainback in the CV's horizontal orientation. It's also about and inch shorter than a PF 25, but since its primary application when released a few years ago was the 8.1L medium duty truck application, it should have plenty of filter capacity for our vintage Corvettes. My understanding is that the PF 25 will be phased out and be completely replaced by the PF 454, so if you wnat originality, you better stock up on PF 25s.
The drainback valve is of no value on a vintage SB or BB, but it is of value on any installation that are horizontal or "upside down" - filter inlet/outlet on the bottom rather than the top as on Vintage Chevy V8s.
Duke -
Re: Oil Filters PF454 Replaces PF25
Duke and Tony-----
Yes, the PF 454 is used for 8.1 L big block truck applications. However, its reduced length was necessitated for clearance reasons in this application. Basically, that's the same reason that the PF-51 (later replaced by the PF-52) was used for 92-96 Corvette LT1 and LT4 applications. There were clearance problems for the PF-25 with the Corvette's left side catalytic converter (dual converters were used for 92-96 Corvettes). The PF-25 was used on 93-97 Camaro/Firebird LT-1s since these cars didn't use the dual cats.
In general, there has been a "downsizing" of oil filters on GM vehicles. I disagree with it. I don't see how, given the same filtering material and internal filter configuration which is common among all these filters, that a shorter and/or smaller diameter filter can filter as well or have as much filtering capacity as a larger one. It just defies "natural laws". That's NOT to say that the PF-454 or PF-52 don't provide ADEQUATE filtering capacity. I'm sure they do or they wouldn't be specified for the applications. But, I just don't see how they can provide AS MUCH filtering capacity as a larger filter. In my opinion, more filtering capacity is always better.
I've always used a PF-35 size filter on my Corvettes. And, I always plan to.In Appreciation of John HinckleyComment
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Re: Oil Filters PF454 Replaces PF25
I have some research (SAE papers) on particle generation and the results are quite interesting. New engines tend to generate a lot of particles during the break-in period, but once broken in, particle generation is very low until the engine reaches end of life where it goes up again. The research suggests that filter changes with every oil change are probably not necessary, and it also tells me that the filter should be changed on new cars after the first two to few hundred miles, but the oil can remain for the full interval.
Insight such as this is probably one reason why OEM filter volume has been reduced over the years, but improved filter media and media pleating has probably not reduced particle trapping quantity as much as the overall filter volume reduction would indicate.
For me the PF 454 is ideal for my Cosorth Vega, both because of the antidrain back valve and because of its shorter length. I could not fit a PF25 on the CV because of the oil cooler adapter and interference with the steering gear. As a result, I've had to use a Purolater PF25 clone for the last 20 years as it has a little more taper on the end and would clear, but just barely.
I'm glad I'm able now to use a genuine AC filter on the CV.
DukeComment
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Re: PF-35
Joe —
Me too. I liked the larger, truck filter.
Until I tried that trick on my '85 with an external cooler. Then, the longer 35 hit something and the entire system down there went to pot. What a mess!!
GeezerComment
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Re: PF-35
Geezer-----
Yes, the PF-35 doesn't work well in all cases. In fact, even on 68-91 engines without oil cooler it "hangs down" a litle lower than might be advisable. That's likely why GM never originally used them for these applications. However, I've always figured that the lowest point is still the oil pan and the apex of the bellhousing. So, if something were going to hit the underside of the engine, the oil filter would be the least of my problems.
However, I would NEVER use a PF-35 if, for whatever reason, it extended below the oil pan or the apex of the bellhousing. With a C-4 equipped with oil cooler, I could see how this could be the case.
By the way, AC manufactures several oil filters which are of the PF-25/PF-35 "family", but are increasingly longer than the PF-35. I wouldn't dream of using any of these on a Corvette, though. Extra capacity does have its limits!In Appreciation of John HinckleyComment
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Re: Oil Filters PF454 Replaces PF25
I ran into the same questions, when replacing the filter on my '72. The 454 is, in fact, replacing the 25. The 454 is about 1" shorter, but otherwise fits fine. The 25 is, however, "correct". The PF25's can still be purchased through many sources, such as Ecklers and Corvette Central...so stock up!
Kevin #39927Comment
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