Generally I would replace every 3-5 years. It is a safety item people I get we all love to be cheap and some of us love to be really cheap (rinse out your condoms they are good for at least 6 more go's) I know we love to believe that the replacement time is all marketing hype so we can save the few bucks on a new helmet but why always so cheap? Sure if it comes down to getting food and shelter vs. buying a new helmet then yeah food and shelter but if not replace your helmet sometimes. Unless you never sweat and never use the helmet in the sun or places that have UV rays and are in very mild temps, you probably want to replace with some regularity.

I know that helmet has your special funk and is growing some really cool mushrooms and is super vintage from the 80s but you don't have to Eroica everything!