When I replaced the thermal paste on my Dell 7750 with Conductonaut Extreme my builds were no longer thermally throttling the CPU.

Do we have any thermal paste or other solution that works for 5+ years without degradation? ( I think I looked into this before but I forgot the answer )

My guess is thermal epoxy will work. But you'll never be able to separate the heat sink from what you attach it to.

I did clean it kinda regularly and did replace the thermal paste once. It stopped throttling when I put it on a stand to provide some airflow from below.