STP fuel system cleaner
 

Would STF fuel system cleaner harm NA motor in FC ?

STP won't hurt a thing.

Got clogged injectors?

dunno yet, got car which was sitting 2 years or so

Ah, in that case don't bother with STP. It's a mediocre product for keeping your injectors clean, but won't do squat if your injectors are in bad shape to begin with. Find a bottle of a premium one shot stuff. I can't think of any brand names right now (it's 5am, and my brain usually turns off at 3:30 or so).

If you can find it, pick up some MMO and Lucas Fuel Treatment to keep things runnign well AFTER you get the gunk out of the injectors. I'll post some brand names after I wake up.

Try Chevron Techron or Redline SI-1. Both actually work decently well. STP and other stuff are just junk.

Read up about fuel injector cleaners here.

Buy a can of BG Products 44K (www.bgprod.com ) available at some Mazda dealers. This is the best fuel system cleaner and only one that will open a clogged injector. After sitting for two years your car needs this product. I have been using a can a year in each car for the last eight years.

The question was answered on the second post: