Your example doesn't highlight something important about this though: they explicitly disclaim the "implied" warranty of merchantability in addition to disclaim

Your example doesn't highlight something important about this though: they explicitly disclaim the "implied" warranty of merchantability in addition to disclaiming all warranties in general. In other words, that means that in your example, you hadn't merely declined to say it works in a car, but you had in fact already said "I guarantee NOTHING about this oil filter; it comes with absolutely NO WARRANTIES", and yet someone would've still called you up and said "despite all your disclaimers you still have an implied warranty because you didn't disclaim it explicitly"... which is far less obvious than what you wrote.