I bought a tube of Arctic Silver 5, like 6 years ago and I still have some left.
It's not like I use it very often and it still seems to work well. I bought it because my old GTX 465 was overheating. I only saw a few degrees (5?) better when replacing the Nvidia TIM.
Intel i5 - 4690K @ 4.5GHz with a Thermalright Macho rev. B cooler set to a very quiet fan profile
= 40C at idle, 70C when rendering 3D images (a much harsher load than most tests).
I use the completely unapproved and WRONG application method of combining Wet and Glob. First I take a very small amount of grease and firmly rub it into both the CPU and the heatsink with a gloved fingertip, to wet the entire surface of scratches, gaps and pores with a micro thin layer. Not enough to see or work as TIM. Then I do the rice grain glob method. And no, I'm not applying too much or having it ooze out of the sides. By wetting first, I usually get nearly full coverage (even though I know you only need to cover the strip in the center).