Thermal paste too old?

[Ruo94]

I did a repaste of my Acer Nitro 5. 

My idle temperature only dropped from 2-3C, and while gaming 4-5C. 

I'm using a thermal paste i bought like 8 years ago for my first build. It's not some brand stuff but both my old and new (2 years ago) PC never ran into any thermal issues with this paste. 
I know that the Nitro 5 isnt the best in terms of stock thermal performance, but i thought it woulda been better after repasting. Maybe I did it incorectly? Or should I get a new tube of thermal paste?

[Ruo94]

for reference, i followed this video for the teardown/repaste. 

 

[Samfisher]

Replacing pastes will only positively impact your testing if it was dried out in the first place.  8 years is also a very long time to store thermal paste.  Thermal paste, contrary to what it's called, isn't a very good thermal transfer material.  It's made to fill all the micro gaps between the cooler and the IHS of the GPU/CPU so that both in full contact with each other.