Is EP worth paying the parts store premium for? No. All things being equal, M1 EP would be my choice out of the oils you listed IF you can find it for a reasonable price (Walmart / Amazon). If availability or pricing is an issue I'd go with either standard Mobil 1 or Pennzoil Platinum. Either of those should be consistently easier to find and at a better price. All of these offerings IMO are top tier and are hard to go wrong with. Just pick your favorite and stick too it. I've never been one to switch back and forth on oils.