Super Lube heat sink compound (good to 500F)
https://www.super-lube.com/Content/I...k_Compound.pdf
States: Thermal Conductivity 0.174 W/m-K
However
https://en.wikipedia.org/wiki/Thermal_paste
"The filler loading can be as high as 70–80% by mass, and raises the thermal conductivity of the base matrix from 0.17–0.3 W/(m·K) (watts per meter-kelvin) up to about 4 W/(m·K)"
Could it be they have not included the metal oxide filler?