Never did figure out who original manufacturer is. But when I changed oil and filter last weekend engine had a STP something or other 10 on it. Expect Filterguy to give me a "atta boy" for my choice of a Champ PH2808! Haven't cut one of these open either, but it's not a Ecore design and feels well built, heavy in hand. Sell Champ everyday, if I can't use it it'd be pretty two faced to install them on customers vehicles! This generator is on a 16'X78' houseboat and engines are 225hp 350 Chev's. Boat was used when I purchased it and had 2 NAPA filters for engines. Saw no reason not to use them .(See post in BOATS forum)
Bob