Amsoil's EaO are made by Wix and (probably) Donaldson where the numbers make sense. I would suspect them to be all US based. I can't confirm that, since nobody at Amsoil will admit to who the actual manufacture is "officially".
K&N and M1 ..and Royal Purple are Champ Labs ..just like the ST ..although the ST, irrc, has sported the "made in Mexico" notation according to some members. The Ecores should be domestic productions and are limited to cans (last I heard) 3" and larger.
The ST's that I have sitting here (3614) have "product of the USA" in the lot code printed across the dome.