What always kills me about these ads for these products is that oil changes are so cheap. I could more easily understand the rationale for these add-ons if it cost a lot of money to change the oil, but it doesn't. I get excellent engine life just by doing oil changes every 3000 miles, or by time in service on my cars which don't get run a lot. (twice yearly). My record so far is one Mercedes diesel, which ran 250,000 miles for me and didn't need an overhaul when I gave it away with a total of 330,000 on it. What's the point in putting an additive in, if you get good performance, excellent wear, and good cooling with regular oil changes? I don't even run them in my marine engines- and they take 27 quarts of oil EACH- twice a year, some years.