I switched from 5w20 for 4500 miles with gains i could see in fuel economy. 28 mpg average
So i went to mobil 1 and now i am getting 2 mpg better. with M1 i am getting 30-31 mpg..
Useless statement without more information like from what oil to what oil (type and viscosity). Back to back runs? How many miles of each for comarison. Highway or city or both. etc etc. Give us more data.