A few years ago Cannondale tried to redefine lifetime warranty as the frames having a finite lifespan, so the warranty on an alloy frame was 5 years and a carbon frame had a ten year lifespan, hence a ten year warranty. That was slapped down, really quickly, because they tried to retroactively apply it to customers who had bought their bikes before they tried this on (this was in the Dorel days) who had the expectation of an actual lifetime warranty on the frame they purchased at the time. I don't know what the current warranty looks like, but I do recall they had to backtrack from this position otherwise they would be on a hiding to nothing with the consumer commission.