I started to realize that getting filter substitutes only involved physical size, and port size. There was usually no factor for filtration or possible other internal attributes. In fact, often the OEM won't even devulge what the filtration requirment is for a given machine, so how can the aftermarket filter manufacturer pretend to sell you the right one?
That's why, I went back to OEM. I own a bunch of equipment and the price of filters add up, but given the possible costs of screwing something up, I am not going to be penny wise and pound foolish as they say.