So ok....I got anxious and added 2oz to my half way tank that had 149 miles on it. I typically get about 280 per fill up of roughly 19.5-20 gallons or 14.4-15.4 mpg. I am not going to use this instance unless I pull about 300-330 out of this tank. That would equal the approx 10 gallons left in the tank adding an additional 20-30% (2 to 4) miles per gallon. I will keep you posted. Thus far I have not heard anything abnormal out of my engine bay and I drove approx 40miles today in my commute and still have the drive home to accomplish.