It is rather used between the processor and the IHS after a "delid".
You can use it on the contact surface with the processor, but it's not recommended for long term use as it can permanently stick the heatsink to the processor, I recommend this one with your Thermal Grizzly Kryonaut (12.50W/m K, 1g)

The MSI 240 specification states that the core is aluminium. Conductonaut, like other "liquid metal" pastes, is not compatible with aluminium.
Aypro's answer is correct.
So is his proposal for a replacement product.