The manufacturer calls it "the greatest breakthrough in the history of lubrication." Indy 500 legend Al Unser appears to risk a $60,000 Dodge Viper to demonstrate its amazing claims.

Prolong engine treatment, $20, is what he touts in an infomercial that has generated many reader inquiries. Por a 12-pounce container of Prolong in your vehicle's oil, the manufacturer says, and it bonds to the engine metal, "creating a low-friction surface one molecule thick." That yields longer engine life, better mileage, and more savings, the ads claim.

The bond is supposed to last even when the oil is drained. In the infomercial, Unser and others drive along a racetrack in the Mojave Desert without oil or oil drain plugs. The same ad, broadcast nationally, pictures a woman who, thanks to Prolong, supposedly drove from Santa Barbara to Los Angeles without oil. (The reason she stopped after 4 hours, 40 miles, 7 seconds? She was hungry.)

We didn't test the other claims, but we did see whether Prolong would protect an engine after the oil was drained.

We installed a factory-rebuilt GM 4.3-liter V6 engine into each of two Chevrolet Caprices. We broke them in with Pennzoil motor oil, changed the oil and filter in each car, and added Prolong to one of them. Prolong claims to work immediately. We drove more than 100 miles, then drained the oil and started driving again. After only 13 minutes and five miles, both engines failed simultaneously.

Today's high-quality oils don't need extra additives. The Federal Trade Commission has told the makers of other additives to stop making false claims. We have notified the FTC about this test.