I have a 91 Nissan 300zxTT (54K miles). My previous oil used was Amsoil AMO 10W40. I do not drive car to often, but I do track gas mileage at every fill-ups. I have been averaging around 19 mpg. I changed to Royal Purple HPS 10w40. I have tracked the mpg at the last 3 fill-ups and I have gotten a consistent 22mpg. I have not noticed any known mechanical or electrical problems with car. Driving habits are the same. I have been using the same type and grade of fuel. I always fill-up at the half way mark. No work has been done to the car.
Could the change in oil have this effect on gas mileage?
Could the change in oil have this effect on gas mileage?