according to my mechanic, this is how fuel system cleaner should be used. 1 bottle of fuel system cleaner to a 1/4 tank of gas. Drive till it is almost empty. Then refill with gas or repeat as needed.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.