In the past when I was young and money was an issue, I did use store brands (Flag, NAPA, Kragen, etc) of motor oil, and I made sure it had the API and starburst symbols that met the requirements for my vehicle. And the correct viscosity of course. This is the basic requirement -- it meets the specs, it is safe to use, and I was never worried about using the store brands. Now that money is not an issue, I use name brands of oil, usually Mobil 1 under the annual rebate which ends up being a ridiculously low price for a top-rated oil. A real no-brainer.