Rust inhibitor

Okay, i'll bite.
Why do you use fabric softener on demo derby car?
It does the same as water wetter. Brings the temp down on the engine and helps keep it from boiling. Believe it or not those cars get so hot under hood they will melt a nylon oil line. If you have ever watched a good long heat or feature you will see the headers glowing orange with flames coming out of them.