Didn't both the Merc and Quicksilver oils have a "Premium" and "Premium Plus" version? I know I purchased and returned the premium in the past after figuring out I grabbed the wrong one.
I really don't know how much difference it would make in those two oils, but the recommendation from Mercury is Premium Plus.
I purchase Premium Plus at Fleet Farm, and I know Walmart will stock it once in a while, but then switch it with Premium. So I am sure to read before just grabbing.
Good luck!