Most of today's engines are designed to run fine at lower octane. You might get slightly better gas mileage from higher octane, at the cost of increased wear on the engine from greater pressure, and at the higher cost of fuel. 91 octane runs around 30 cents per gallon higher than 87. That's around 20-30% difference at the pump. Average mileage increases by about 1-2mpg. That's 5-10%. So you're paying double the cost that you might save on fuel economy. Now factor in the greater wear and tear.
Simple math.
You will find guys all over the place on this. Some are religious in their beliefs that higher octanes are better. Well, they are, for engines designed for them. For engines designed for lower octane, they're not.
Simple math.
You will find guys all over the place on this. Some are religious in their beliefs that higher octanes are better. Well, they are, for engines designed for them. For engines designed for lower octane, they're not.