Oil CAN Save You Gas

Many factors are involved in determining the overall fuel economy obtained when driving a vehicle. One of the factors is the fuel efficiency of the engine oil being used.
In addition to being rated on the basis of their performance and viscosity, oils are rated on their ability to reduce the amount of fuel consumed during driving. Oils are rated against a reference oil in a standard engine test much like the ones described earlier in the "Oil Performance Ratings" section.
In this particular test, the fuel economy is measured and compared with that of a reference oil. If the tested oil provides at least 1.5 percent better economy than the reference oil, it is labeled "Energy Conserving II." These energy conserving designations are indicated on the lower half of the API logo to indicate fuel efficiency.
Energy Conserving II oils should provide the best fuel efficiency followed by Energy Conserving oils, and finally, followed by the lease fuel efficient oils, ones that don't contain either designation.