I bought a bottle of Prolong Engine Treatment at Pep Boys after seeing their infomercial on TV. The label reads, "Contains patented formula. US Patent 4,844,825." So, I took a look at the patent. One thing the patent addressed that really concerned me was corrosion.
The infomercial shows Prolong being poured over a nut in a test tube. Then, they apply heat. In a short time, they remove the heat and claim that Prolong does not break down under heat. This is a load of bull.
I did the same thing and Prolong bubbles and boils like a witches brew, turns black, and makes a thick film of crude that covers everything. It is absolutely worthless and can completely ruin an engine.
DO NOT USE this trash.