My mileage is now back where it was and the engine is smoother.
I recently replaced the fuel sending unit in my Xterra which Nissan would not cover. I just came out of the warranty by a few miles. First tank, my mileage was off by 30 to 40 miles. I pulled the battery cable to reset the ECM. I was only off by 20 to 30. I went and got some Lucas and poured it the tank. My mileage is now back where it was and the engine is smoother. This is good stuff. It blows away anything else in a bottle.