I dumped a gallon of Seafoam in my 75 gallon gas tank. I had changed the fuel filter maybe 2000 miles previously. I drove the coach another 1500 miles and the fuel filter was so plugged that I had to change it again. Don't know if the Seafoam did anything for the injectors, but it darn sure knocked dirt loose from somewhere.
Also, before anyone says anything, that's only 1.7 oz per gallon. The can recommends 2 oz per gallon for injector cleaning, so I didn't overdose it.