"Try Vaseline as a sub for dielectric grease. It'll melt real fast though some remains."
RustyNails, fwiw... I used to work in the h.v electrical utility field and oilfield equipment support yards.
It is not recommended to use Vaseline or any other petroleum based products on any natural rubber gaskets, o-rings, insulating materials, etc. As the petroleum base tends to break the soft rubbers down.
That as as per manufacturers. One thing I don't understand and I always questioned was, well we use rubber hoses for fuel, some diaphragms on pressure switches and valves that carry oil, diesel, gas, kerosene, etc. are made of rubber then what about that?
I could not understand it, but something is better than nothing to keep the rubber insulators from sticking on the plugs.