An engine additive product seen on TV and in many auto supply stores across North America.

It claims: zMAX is a unique metal saturating Micro-lubricant refined from one of the purest forms of petroleum. zMAX has a scientifically modified molecular structure which allows it to soak into the metal.
It retails for about $40 and comes in three bottles, which you add to your engine's oil, fuel and transmission fluid. According to the box, it cleans your engine, improves your gas mileage, reduces emissions, and increases power.

In reality, zMAX is nothing more than tinted mineral oil and does not deliver any of the performance gains it promises. In fact, it produces more than twice as much bearing corrosion than motor oil would by itself. The Federal Trade Commission has filed suit because of this.

Caveat Emptor.