My bulk engine oil tank is getting low, I called a Shell jobber and was going to order Rotella or Rimula and he was telling me about the Service Pro brand they also handle. He claimed the quality was just as good but because there was no marketing budget it is priced lower.
I never heard of it before, he said that many new car dealers use it and it is approved(with certifications) for all warranties.
I would like to hear from someone with experience. $2-3/gal difference is substantial.