Most generic gas stations buy their gasoline from the least expensive source including refiners who will neglect to add engine-protecting detergents to their gas. They save a few cents per litre over the branded stations which are more reliable so their prices are more competitive. The lack of detergent in this type of gas will mean that your fuel injection can get clogged more easily and cause increased wear on your engine.
Some signals your car or truck may be sending that you need to flush your fuel injection are:
In addition to using top quality gas, be sure to change your fuel filter at least once a year.