Just purchased STP cleaner from pepboys yesteryday. Anyone use them before? I plan to use it on a 98 Integra and a 2000 Civic. However, i heard they may harm the engine.

 

they are ok, just make sure you go through the tank quickly. They have solvents that tend to eat rubber orings and the like if the treated gas sits for a long while. I use the shell vpower additive twice a year in my g sedan when I take a long roadtrip. I still get 26-27 mpg on road trips.