I got moly at 12 k miles. Through this brutal winter my worst tank was 26 when I drove smaller trips. It has stayed similar to my summer mpg. So from my experience its about 1 to 1.5 mpg.What kind of fuel economy gains do you get from the moly?
Moly oil is respected across brands. Its not easy to find unless the dealership stocks it. Else its eBay.