I'd use either, similar media type description. M1 in WM is more expensive that Ultra though, so daily price latter the choice there. M1 touted more as an extended oci filter, post use anecdotes here have looked good. Standard Wix/Napa Gold, ~7500 mi with10k mi doable. If one is lucky to live where local Napa has Gold sale, they can be obtained ~$4 on sale.
As for off topic, unaware of reference with no citing. Wix now has the factory FoMoCo factory OF contract, Champ used to have. Other than that afaik, status quo to past, no relationship.