That oil filter research was done by Dempsey Bowling., who did the cut-up analysis during his college years, in his dorm room, as I recall. I found it on the online (Yahoo! ?) group "Shelby Dodges and Turbo Chryslers", or similar. It was quite revealing, even found the famous-brand Frams used cardboard for their media end caps, which shook the car world, by observation. The high-pressure relief valves were usually flat springs, as others were coil springs (coil springs deemed to be better and more consistentg). There was no mention of the media, just construction and such. Some brands used a silicone rubber drainback flap as others used a lesser grade of rubber. He had pictures of all of these things on the website, too.
Later, "Auto-X" magazine did a filter comparison using the FL1A filter application. In that test, Wix suddenly came out the best as to construction, including the coil spring blow-off valve item.
From reading about oil filter specs and tests on
www.bobistheoilguy.com, there can be some large variations in the quality of the filter media, as to just how far down in size the medial will catch. Seems like the methods used to test these things might be a bit questionable, too! But it can be a big balancing act of sorts. The finer particles that get stopped also mean more flow restriction, very possibly. Which means that when the flow restrictions happen, especiallhy on a cold engine with thicker oil, the more oil that will bypass the filter media as a result, due to the internal blow-off valve sending the unfiltered oil back into the system. Eventually, though, as the oil warms and rpm/flow decreases, most of the oil will go through the oil filter. The sizes of the grit that does pass through the filter can be a big balancing act. With the viscosity of the motor oil in the mix, too, as is "engine sealing to the outside world".
By observation, almost all of the old-line car repair/maintenance brands that were their own company back in the 1950s (earlier and later) are now a part of TWO (maybe three) large holding companies. Not unlike Holley becoming a "one-stop shop" for hot rod parts, seemingly over the past decade. Holley is not just about carburetors any more. As other smaller North American brands have surfaced that might be better than the old-line brands might now be.
In this part of the world, down here in DFW, TX, all of the service stations stocked either the Fram or Ford-branded (FL1A) filters. Purolator was a the auto supplies, usually, and well-thought-of back then, having been a dominant oil filter brand from the early days of autodom. The Exxon guy we ended up using in the 1970s (after our Gulf/Chevron guy sold his stations) was a Ford guy and kept the Motorcraft filters for Ford applications in stock, so as they also fit Chryslers, that's how we got in with that. Seems that others did the same, too, as I found out years later from others in our Mopar Club.
Personally, knowing that an OEM-spec part meets the OEM's minimum spec, at the least cost, I might trust their brands a bit farther than some private brand, with the name brand private company parts being next in line . . . UNLESS I'd found something better than the OEM item (quality-wise, including cost, or a better place to buy them).
Only thing is that we never know how well an oil filter or motor oil might work until the engine is torn down for rebuild, years later, after the fact. Until that time, everybody makes the best decision for their region/area of the nation as to what to use.
Zinc in motor oil? That's another issue.
Enjoy!
CBODY67