Billings Gasoline

I overspend on my vehicle maintenance. I always run the 91 octane premium in everything from my pickup on down to my leaf blower. But, I know nothing about the 3 refineries in our area.

Does Conoco outperform Exxon? Or does Cenex have the good stuff?

Can the average consumer even tell the difference between brands, or are they all really good?

Let me know what you use and why.