Ur right. Since its only few bucks worth the peace of mind. 🙂 thanksI would toss it out, and buy some new. A couple years, I'd say use it. But at 5 years old, it's only a few bucks to get another tube. But some people will tell you it's fine as long as it hasn't separated, and to use it. For me, a few bucks to know it's protecting an expensive CPU is worth it to me.
looks like i'm late to the party; but this thread intrigues me, so i'm going to give my opinion.
TIM is in a way or another a liquid metal, or rather a composite paste of materials of which none should evaporate, much less do so from inside a tube. nor should they undergo any chemical reaction. i would imagine thermal paste would have a shelf life measured in decades, not years. What exactly could happen to a TIM left sealed and not exposed to heat?