[78w72]

For those of you that have to use a smaller diameter oil filter on Pontiac V8s with headers, what brand/# filter are you using? How long between changes? Any lower PSI issues compared to full size?

Ive been using the full size Mobil1 filters that fit my 78 TA 400 with Hedmann 28150 headers, have used a wix 51258 before too, both were a tight fit but was able to get in/out pretty easy... i use a ziplock bag around the filter to catch any oil since it does need to be tilted a little to come out.... but I ran out of my stock of Mobil1 filters and decided to use a cheaper priced STP S25 filter that says it replaces the wix 51258 full size filter... its actually a little bigger diameter & wont fit between the headers & bellhousing... so I checked the website & they offer a s3675xl that is narrower but a little longer filter that replaces the 51522 or AC PF61. Just curious if anyone using the smaller filter noticed any issues as mentioned above.

One interesting thing I noticed is a bulletin stating the filters have been redesigned for better flow, they show pics of the old back plate with small holes vs the new design with more holes that are a lot bigger to improve flow.... for the S25 filter vs the S3675 there are twice as many holes & they are much bigger.

Also noticed the flow rate published for these STP (champion labs) filters at 15gpm, havent seen that spec published on too many other filters, is that good or bad compared to other name brands?

https://contentinfo.autozone.com/zne..._baseplate.pdf

[Jay S]

51045 Wix is what I use on my Pontiac’s with headers. I block the bypass also, full flow thru the filter. It is slightly bigger than the 51258, it seems like I recall the 51258 has a drain back valve in it and the 51045 does not though, really not an issue for a Pontiac though. I don’t do anything different on oil change intervals with the 51045, it is decent sized, 51258 is noticeably smaller.

[65 Lamnas]

Does the "Jim Hand modification" to the oil filter housing simply not work for people? It's worked every time I've tried it.....and BTW...I'll only run a Baldwin B39 these days.

[chuckies76ta]

Just an observation. I believe GM L5P diesels went with the new oil filter PF63 which is probably the same size your talking about. I'm thinking if it can work on that engine you should be fine with a smaller filter. I know one is metric and other is SAE. I personally don't care for the smaller filters on large engines.
I run the Wix 51258 on my car, but I have to remove the filter housing to change oil. I can't see any issues from running the smaller filters. Sorry not much help to you.

[78w72]

Originally Posted by Jay S

51045 Wix is what I use on my Pontiac’s with headers. I block the bypass also, full flow thru the filter. It is slightly bigger than the 51258, it seems like I recall the 51258 has a drain back valve in it and the 51045 does not though, really not an issue for a Pontiac though. I don’t do anything different on oil change intervals with the 51045, it is decent sized, 51258 is noticeably smaller.

Not familiar with that # filter, but if its "slightly bigger" than the 51258 then it definitely wont fit for my combo of a 4 speed TA with hedman headers but is also not one of the smaller filters I asked about.

Originally Posted by 65 Lamnas

Does the "Jim Hand modification" to the oil filter housing simply not work for people? It's worked every time I've tried it.....and BTW...I'll only run a Baldwin B39 these days.

This car does have the jim hand mod to the housing, it helps with other filters but still doesnt allow the big STP or similar sized filters to work on this car.

Anyone using the smaller filters mentioned?

[78w72]

Originally Posted by chuckies76ta

Just an observation. I believe GM L5P diesels went with the new oil filter PF63 which is probably the same size your talking about. I'm thinking if it can work on that engine you should be fine with a smaller filter. I know one is metric and other is SAE. I personally don't care for the smaller filters on large engines.
I run the Wix 51258 on my car, but I have to remove the filter housing to change oil. I can't see any issues from running the smaller filters. Sorry not much help to you.

Yeah I think the PF63 is the SAE version of that PF63 but same size.

Based on the bulletin it seems like they (champion labs at least) improved flow on the smaller filters so should flow close to or as good if not better than the older big filters, just less capcity.

Anyone have flow rate numbers of other filters to compare to teh 15gpm of this STP?

When I couldnt get the big STP in I was debating on pulling the housing, but would rather not have to deal with that & new gaskets everytime I change the oil/filter, I dont think there will be any problems with this new smaller filter, just change it earlier of the capacity isnt as much as full size filters. One big benefit I noticed right away is there is a LOT more clearance from a header tube so it wont cook the oil in the filter as bad.

[Jay S]

The 51045 is not that much bigger than the 51258. It is bigger though. It is what I have in my 77 4 speed TA with 1 3/4 D port Doug’s.

[78w72]

Originally Posted by Jay S

The 51045 is not that much bigger than the 51258. It is bigger though. It is what I have in my 77 4 speed TA with 1 3/4 D port Doug’s.

Thanks for the input, but for my car being bigger than a 51258 definitely is in the wrong direction... dougs must be routed different than these hedmans or that 51045 is not as big as the S25 STP i tried.

[sdbob]

I've used the block off ever since HO Racing recommended it. I've used Fram HP filters,lately NAPA gold. In my SDs. I'm still learning, well I hope.

[Jay S]

15 GPM is quite a bit higher rating than any of the small Wix filters I have seen. They are 12 at best.

[64speed]

Purolator PBL25288

[Formulas]

i would rather change out a small filter mid oil change than un'bolt the whole filter adapter for a larger filter

[Dragncar]

I would not block the by pass running a smaller filter.
I know people do it, just not me.
My current engine has the by pass blocked, but I run a K&P screen filter that has a huge flow rating. It also has a built in by pass but it should not ever by pass. Have it for safety reasons.

[BB70]

No room here also for a standard diameter oil filter. I have been using a Baldwin B 30.

John

[grandam1979]

Bosch 3423 works great in tight areas

[Jay S]

The Bosch 3420, Baldwin B30, and Wix 51045 interchange. Most of these small filters sub too either the 51258 applications or the 51045 applications. The Perolator PBL25228 mentioned subs to the 51258.

I guess it depends where it is tight. Here are some specs too compare.

[chuckies76ta]

Originally Posted by Formulas

i would rather change out a small filter mid oil change than un'bolt the whole filter adapter for a larger filter

Your absolutely right, but it's not a problem with the car on the lift. I only change oil once a year also.

[phil400]

Just asked My buddy with same car and headers runs wix 51042 or Quaker Stake 3675

[78w72]

Thanks for the replies, sounds like most in this situation run the narrower filters of varying brands, not too many addressed the questions about any of the possible issues like psi drop...

But after installing the s3675 that the link above says is redesigned for better flow, I noticed no difference in psi on the gauge, the other benefit is the added clearance from hot header tubes vs full size filters.

As for capacity, it might be slightly less than the full size but based on the shape since its longer that accounts for being narrower, I dont see an issue with clogging or bypassing the filter due to slightly less capacity... this is a newer rebuilt very clean internally engine that doesnt see daily use or high miles each year so theres not really any "dirt" to clog the filter as fast as some have suggested.

Thanks again for the input, my experience says the smaller filters are perfectly fine to use when space is limited.

[Jay S]

The factory stock bypass will send oil thru the bypass if there is extra restriction. You would not likely have a change in oil pressure with a smaller filter even when it starts to plug up.