I was pleasantly surprised yesterday.
The Costco Interstate in my pickup had not been holding a charge well.
So since we had a 55 degree day yesterday, I broke out my never used, no-name battery tester from Amazon that I purchased as the result of a tip from here.
After an extended period on the charger, I tested the three year old battery (almost to the day) and it tested "Poor."
So I went to Costco. Seems that they decided that group 58 (and 59) batteries should be excluded from their rack. They generously offered to order me one. He "Thought" he could get it shipped in in two weeks.
I declined and decided to head to Rural King, because I knew that they stocked them.
As I was driving there, I thought that I may as well go into WM, because I actually had to physically drive past it anyway.
So I went in. They had several of their "Plus" batteries, and one was actually stickered reasonably (1/25), and was actually a couple of dollars less than RK. So I went ahead and purchased it.
I thought at the time that the battery looked strange. Nothing really could be determined from the serial # in regards to manufacturer. It did claim to be a Mexican product.
When I got home and the the warranty receipt, it showed the EP code on it. It used to be that to get an EP battery in my area, one had to go to Canton to get it, as that was as far east as the WM EP batteries were distributed.
However, on the other hand, the RK battery offered was clearly from the vent design a Clarios. Anymore, who knows?