[obermd]

Run your current tank down to the Low fuel light. Then get a bottle of Techron Fuel System cleaner and go to your nearest Shell station. Pour in the fuel system cleaner in and then top off the tank with the Shell vPower Premium. On the 2011 - 2016 LTD ECO MT this means you'll want to fill past the artificial shutoff. You want the fuel to be visible a couple of inches down in the fill pipe when you're done. The fuel system cleaner will mix with the gasoline in the tank. Drive the car until it's "empty" again and then refill with the Shell vPower premium to your normal first click fill point.

This procedure does 80% of what the injector cleaner service at the dealership will do and do it for less than the dealership, just the cost of the cleaner and the incremental cost of Shell's top of the line detergent package.

 

[obermd]

Really no definitions on what top tier gas is, only use this stuff, but still has carbon in it, carbon is the problem.

All gas has carbon. Gasoline is a distillation of crude oil, which is a complex hydro-carbon.

The Top Tier program has specific requirements that must be met, but it really boils down to additives that prevent carbon build up and clean underground tanks and distribution channels.