Noooooooooo!
Absolutely not! under no circumstances, ever...
You might well void your warranty and it is very unlikely to do any good. Do an internet search on it (and all the other various magic potions you can put in your engine) and you'll find all sorts of stories for and against...
...but the "against" ones usually have some scientific basis and the "for" ones are usually anecdotal.
Honestly, properly serviced, engines last a very long time. The body usually rusts away on most cars before the engine dies (assuming no inherent design faults and proper servicing). My own car is 16 years old and has over 220,000 miles on it. The engine is fine (burns a bit of oil now but not enough to visibly smoke or fail its MOT). The body, however, is not long for this world!
From memory, some manufacturers wouldn't honour the warranty on engines treated with teflon-based additives because the teflon particles would clog the oil filter and this, in turn, would then open its internal pressure relief valve and effectively take itself out of the circuit. I'd much rathre have the benefit of a decent oil filter than a bottle of magic gloop any day!
Going back to Paul's watch analogy on the Safespeed home page, you can imagine that Peugeot have probably spent a bit more developing the engine than Rolex might spend developing a watch. You wouldn't dream of buying a new Rolex, prising the back off and giving the cogs a squirt of WD40 just to try and improve things by reducing friction would you?