Prolong, like most other ''miracle additive'' manufacturers have been sues (and lost) by the Federal Trade Commission for false marketing and advertizing statements and unproven claims. Prolog contains the same base additive as Duralube and MotorUp (probably others) which is a chlorinated mixture of kerosene (up to 80% kerosene) and detergents.
Check this link:
http://www.greasedlightning.com.au/information/chlorine.htm
JackD