My daughter gifted me with this fuel system cleaning kit for Christmas. She received it as a free trial sample from the company's marketing department. I just treated my turbocharged Chevy HHR/SS with 88K miles. I've tried other similar products before, and I have to say this was very easy to use. The instructions were very clear. I used an alternate manifold vacuum line (rather than the recommended brake booster line) because it was easier to get to and was more centered on the manifold thereby getting a more even treatment to all 4 cylinders. I could definitely smell the 'rotten egg' odor from the deposits loosened from the idling engine. The full treatment took only about 5 minutes. There were NO problems with engine trouble codes or anything. After treatment the engine does idle smoother and has all the power GM intended. It definitely did no harm, which is always my first concern with using a new product. I'm very particular about my auto care and I did some research on this before using it. So far, I would definitely recommend it and I will use it myself again after my next oil change. Mobil 1 only of course!