Store Bare Engine Block
From Wikipedia:
Chemically, cosmoline is a
homogeneous mixture of oily and waxy long-chain, non-polar
hydrocarbons. It is always brown in color, but can differ in
viscosity and
shear strength. Cosmoline melts at 113–125 °F (45–52 °C) and has a
flash point of 365 °F (185 °C).
I have known of people to leave firearm parts in direct sunlight and then use a shark handheld steamer to remove it from fire arm parts. Chlorinated brake cleaner (trichloroethylene) works the best of anything I have tried but would probably get expensive quickly on an entire engine block. Diesel fuel works wonderfully, though.