Does Thermal Paste Expire?

[lettuce]

Have had some Arctic Silver 5 for about 8 years and am just wondering if it loses some of its ability to cool over time or even expires completely, the paste itself hasn't gone hard or watery and still looks like it did when first opened.

Also what is considered the best paste in 2019 still Thermal Grizzly Kryonau or Noctua NT-H1?

 

[lettuce]

Thanks for the replies. Yeah ive used the same tube of AS5 for about 6-8 different builds (family & friends) over the 8 years or so ive had the paste, so has been open and used a few good times and not brand new never used stuff.

So if im want to reapply AS5 to my cpu its best advised not to clean the cpu with rubbing alcohol etc removing all traces of AC5 completely and instead just wipe if off with a cloth?