Why is my MacBook Pro 2013 (15") new replacement fan noisy?

I just installed a new fan in my MacBook Pro (15 late 2013) and it’s significantly louder than the old one. The new one is on the left, and the old one is on the right, the left one wore out (very noisy, flocked bearing), so I replaced it, but I notice the CPU is still hitting the +90 C zone so I'm wondering if I need to do the thermal paste as well. Do laptop fans have a wear in period? The paste I'm looking at is Grizzly Kryonaut.

Question by Quinnjin Williams on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.