A few months back they had a placard on the pumps stating all the benefits that the new Plus states. Then they had an article in their magazine about how they worked with Lubrizol to formulate the new additives. I believe your stations already has it.
I'm going to be honest I didn't know costco sold top tier until a week ago and i've been filling up there for over 5-6 years. I never read anything on the pump beyond the octane, price, gals and where the skip/no words are on the screen to press the corresponding button. I imagine a good 99% of average joes and janes don't know what top tier is and that costco sells it. When I first heard of top tier gas I just imagined big name brand gas stations not an actual specification. That makes costco a better value proposition than I thought before.
To be honest, I used nothing but Sheets regular in 2 company cars and never had any gas related problems. They could have had all kinds of deposits when I turned them in but they ran ok. That's not TT gas.
my reason for using Costco gasoline was that they built a station close enough to me and that it was Top Tier since 2014 for me...no issues in cars I take care of whether 87 or 93 octane...