[77 TRASHCAN]

51049 does not have a drain back valve, never has, neither does the 51258 (the shorter version of the 51049)

The Chevrolet V8 filter 51061 (same size as the 51049, different gasket size is only difference...), got changed around 1987 when complaints started coming in about knocking on cold start up. Going to 5W30 oil may have contributed to the problem. They went to the 51060 filter WITH the drain back valve. It supposedly keeps oil in the engine after shutting off.

There's been many conversations about filters here. I used to sell Wix filters. We had a bunch of the competitors filters cut open, on display to show the difference. Fram was a big joke, the cheapest looking...
There ARE filters that look better than Wix, when cut apart, not many though. K and N used to be a good filter. The LEE 2 stage was a good one, also. Baldwin looked OK, not as much filter paper as Wix. Many here have bought Baldwin, giving them the nod of being a absolute top notch high grade oil filter. My grade for them would be a "B", Wix being an "A", The old K and N, would be an "A+"

I've mentioned it before...how good does a filter have to be? How good, is good enough??? The new possible down graded K and N must NOT be good enough.

My engine builder (this was 20 years ago) used Fram. I talked to him about the cheap design. He said he never had a problem from them...I sold Fram, before we changed to Wix. Only had one filter promlem. A 350 Chevy inboard boat engine. Had pin holes in the filter can. Made a mess in the boat. Fram made good on the problem.

Next...

[Navy Horn 16]

There they are side by side. The K&N has small discharge holes, the WIX has larger ones. The K&N also has a much more the convex center that puts the threads way up closer to the gasket height. This damn thing wouldn’t seal though.

[77 TRASHCAN]

Hmmm, that red rubber piece looks like an anti drain back deal. Wix book says no, though.

Take the rubber gasket off the KN and lay a straight edge across the opening. See how close the gasket receiver grooves are to the top of the threaded boss....

[Navy Horn 16]

Originally Posted by 77 TRASHCAN

Take the rubber gasket off the KN and lay a straight edge across the opening. See how close the gasket receiver grooves are to the top of the threaded boss....

With the gasket on and no compression, there is 3/32 space. With the gasket off, it's about 1/32. Really tight.

[77 TRASHCAN]

Originally Posted by Navy Horn 16

With the gasket on and no compression, there is 3/32 space. With the gasket off, it's about 1/32. Really tight.

Uhhhhh, with 1/32 difference, the threaded boss may be bottoming out, not allowing the gasket to compress enough...maybe..

How is the Wix filter???

[Navy Horn 16]

Originally Posted by 77 TRASHCAN

How is the Wix filter???

7/32 with the gasket still in, 5/32 with it out. So, a lot more clearance.

[Baron Von Zeppelin]

i don't remember the K&N looking like that up top, the last time i checked them out in the store. It looks a bit cheapy compared to the Wix or a Mobil 1 in that area.

Looks like you found the source of the leak problem though, in the measurements.

[hgerhardt]

If you really want a hex on the bottom AND full-height AND made in the USA, get a Champion CH48104-1. Those are what I use on my Lycoming. The filter adapter and fuel pump are AC products, which is why these filters fit Pontiacs too. A bit pricey at $28, but you can find them way cheaper on ebay.

[Tempest T-37]

You may want to look into the filtration media used in the K&N as well, I remember reading that one of the more expensive filters (it was either K&N or M1, can't recall which) actually has a larger micron media. So it would flow better but filter worse than a competitor, similar to the air filters.

[Region Warrior]

K&N products are over priced junk.

[Sirrotica]

Originally Posted by Tempest T-37

You may want to look into the filtration media used in the K&N as well, I remember reading that one of the more expensive filters (it was either K&N or M1, can't recall which) actually has a larger micron media. So it would flow better but filter worse than a competitor, similar to the air filters.

Right from K&N:

K&N automotive oil filters provide high flow rates while providing outstanding filtration. High filter flow rates are especially important in racing vehicles where heavier grade oil is used and the oil is pumped much faster than in a standard vehicle. K&N automotive oil filters are engineered to handle all grades of synthetic, conventional and blended motor oils.

So the answer is yes, that the filters have larger pores in the media that are in the interest of not impeding oil flow in the sacrifice of filtering quality. Their air filters use the same philosophy, larger pores sacrificing quality of filtering. You might as well use window screen, lots less restriction for either filter, air, or oil.

And the whole problem goes back to putting an oil filter between the oil pump and the internally oiled engine components, It's just a poor design, because it can't be efficient, while being low restriction. If it actually did the job of keeping the oil clean, and avoiding removing the fine wear items from the oil you wouldn't have to keep flushing the engine with fresh oil.

If you're running a K&N oil, and air filter, you better be flushing the oil really frequently, because neither filter is removing the small particles that end up in the oil. They're saying their products are designed for racing, and frequent oil changes and frequent tear downs. I'd be avoiding their products for street use and durability.

Probably one of the finest spin on filters in my research is the Purolator Boss filter, made by the Mann Corporation. Mann corp. purchased Purolator within the last couple of years. Mann oil filters has always been a well respected name in the premium oil filter arena.

The media of the Boss filter is synthetic, and has a more consistent pore size than cellulose (paper) does. It's not going to be on the level of a by pass filter, but it's a premium oil filter if you're intent on just keeping the factory design intact, without actually spending any money, or time, to improve your filter system.

From the Purolator Boss site:

Choose PurolatorBOSS® for these driving conditions:
Heavy, congested traffic
Frequent short trips and stop-and-go driving
Towing - boat, travel trailer, utility trailer, jet ski, etc.
Off-roading
Extreme temperatures — hot or cold!
Extensive engine idling and frequent engine stops
Mountainous terrain
Dusty conditions - dirt/gravel roads, construction sites, farms, off-road, etc.
Explore the Purolator Oil Filter Guide to learn more


Experience the power of PurolatorBOSS®:
Up to 15,000 miles of engine protection
PuroSEAL Gasket™ made of ethylene-acrylic for longest life
Silicone anti-drainback valve protects against dry starts
Double-helix metal center tube for optimal oil flow
Heavy duty BOSS Steel Casing™ for greater durability to withstand extreme pressure
Over 99% Dirt Removal Power™
Rugged internal construction
Available for the most popular vehicle applications — domestic or import

http://www.pureoil.com/en/do-it-your...urolatorbossr/

I try to use the Boss filters on anything I don't have a by pass filter on. I just did the first initial oil change on my Kawasaki powered Ariens zero turn and used one of these filters, with Pennzoil Platinum synthetic oil.

Good read here about spin on oil filters and the differences, ratings etc:

https://theshopmag.com/features/oil-filters-exposed/

Here's one from Jeff Smith that cites the GM study about how wear is compounded and reduced by filtering out the sub 20 micron particulate that conventional filters leave in the oil to recirculate. He's talking about Fram filters which isn't my choice:

https://www.onallcylinders.com/2015/...ur-oil-filter/

[ZeGermanHam]

I'm also of the belief that K&N products are overpriced, lower quality, and do not provide the same level of filtration as other filters (applies to both oil and air filters).

[64speed]

There is no Purolator Boss crossover to the 51258 Wix though. That sucks

[Kenth]

Originally Posted by 64speed

There is no Purolator Boss crossover to the 51258 Wix though. That sucks

Looks like the Purolator PBL25288 is a Boss crossover to the Wix 51258 and ACDelco PF24.

[Dragncar]

Originally Posted by hgerhardt

If you really want a hex on the bottom AND full-height AND made in the USA, get a Champion CH48104-1. Those are what I use on my Lycoming. The filter adapter and fuel pump are AC products, which is why these filters fit Pontiacs too. A bit pricey at $28, but you can find them way cheaper on ebay.

Thanks for this, if a filter is aviation rated they are top notch. Have to be.

[Dragncar]

Originally Posted by ZeGermanHam

I'm also of the belief that K&N products are overpriced, lower quality, and do not provide the same level of filtration as other filters (applies to both oil and air filters).

I used to race my Tundra(wife) in Sportsman class. Tundra is stock, ran down to 14.56 just driving it out there, letting the tires down to 20lbs.
Bought a "K&N" air filter, expensive. Truck slowed down.
Some of it is the computer slowing down lead foot operation, but I was not impressed. Maybe Toyota knew something K&N did not.
I do run a K&N velocity stack on race car, works fantastic.

[Tempest T-37]

Originally Posted by Dragncar

I used to race my Tundra(wife) in Sportsman class. Tundra is stock, ran down to 14.56 just driving it out there, letting the tires down to 20lbs.
Bought a "K&N" air filter, expensive. Truck slowed down.
Some of it is the computer slowing down lead foot operation, but I was not impressed. Maybe Toyota knew something K&N did not.
I do run a K&N velocity stack on race car, works fantastic.

Off topic, but it was likely due to the K&N oil migrating from the air filter to the MAF sensor. They do work well IF the filter is a bottleneck, but there can be side effects if using with a mass airflow based EFI system (unmetered air getting by the oily/dirty MAF and causing a lean condition). I've used them on my turbo Subarus without too much trouble, you just have to clean the MAF more often. I tend to be pretty light with the K&N oil when I clean the filters because of this. I had one on my P350 as well for about 20k miles (that I'm currently building) but it was a low comp, 2bbl so I'm not sure how much difference it really made. The cylinder walls look totally fine, but there's a lot of carbon in it (It had also a stuck PCV when I got the car though.)

[64speed]

Originally Posted by Kenth

Looks like the Purolator PBL25288 is a Boss crossover to the Wix 51258 and ACDelco PF24.

I will have to look that up. I used the purolater website and it only crossed to regular filters

[GTOLou]

Happy w/ the HP2006 - headers, 2nd gen. dport. Tight space. Fits well - can get it off and on fine.

[The Champ]

Link to Purolator Application Chart:

https://www.pureoil.com/en/do-it-you...filter-lookup/

Go there, insert PBL25288 under part number and it will list all the applications, which include the Pontiac 455 as well as 400's and 428's. For some reason the listings don't go back far enough to include 389's - but we all know that the 389 will take the same filter.