whopper

Do not use that pipe wrench on the filter cap again!!!

Don06

I don't know how long it's been since AC made their own filters. Probably more than 30 years. Most filter brands are made by outside manufacturers. I was at a Hutchens plant in 1988 that was making filters under 17 different names. Baldwin and Wix still make their own. I'm not certain about Fram. They make some of their own and manufacture for others but I seem to recall them outsourcing some. Delco contracts with whoever makes them the cheapest to the specifications Delco sets up.

For engine oils, 5 microns is about as fine as is necessary but the total area of the media is also very important. Either the filter or the engine has a bypass valve that allows oil to bypass the filter if the pressure gets too high. In cold weather the oil is thicker so it is more difficult to push it through the media so it bypasses. This is one of the reasons it is important to warm up the engine in cold weather so the oil warms and flows freely before increasing engine speed and pumping more oil.

The more media area a filter has, the better it can handle the cold oil and the more dirt it can hold before it plugs up. Of course, the less media the manufacturer puts in the filter, the lower the cost. Different types of media work better but cost more. Paper is the cheapest and most used media but it can be pleated to provide much more surface area in some filters than others. Polyester media is more expensive but it can hold more dirt. Once the filter media fills up, the pressure goes up and the bypass valve opens so your oil is no longer filtered.

I don't know how fine they make the stainless steel screen filters nowadays but 10 micron is about as fine as I have seen