Well the explanation of what Dielectric Grease is threw up a red flag for me as not being good at transferring heat at all.
Anything that would Insulate the CPU heatspreader from the Fan/heatsink can't be good...
"
Dielectric greases and insulating fluids are insulating oils, greases, transformer oils and fluids that have a high dielectric strength and are used in transformers, capacitors, EDM machining, and other electrical device applications."