Protection First Class offers an inexpensive alternative to rubberized undercoating.  This rust preventative remains soft and flexible. It will actually create a self-healing barrier. PFC continues to stay on vehicles long after other water-soluble or solvent-based products have evaporated or worn off.  Another great feature of PFC is that its translucent film is easy to see through and diagnose problems before they happen, unlike rubberized undercoating, which masks the problem and allows rust to grow and spread under its surface!  PFC lasts for up to a year and is easy to remove. It is also inexpensive and easy to reapply. To apply, first, clean the vehicle thoroughly. Then remove and scale the worst of the rust away. Next, shake PFC thoroughly before filling the spray gun reservoir. Now, you are ready to apply an even coat of product to the vehicle's undercarriage.