That's not true at all. Thermal paste can degrade over time. Any Thermal paste.
You can pick up some tg-2 from Thermaltake at Best Buy. I suggest not getting the cheap brands.
Take the old cooler off, use alcohol to remove the old paste from the CPU and heat sink and apply a pea size glob on the processor.
You then put heat sink back on making sure it's on snug. Speaking of the cooler, I would make sure it's on there tight before doing anything else. Stock intel coolers can be shit.