Ah crap, hit submit too fast.
Diesel engines work by igniting the fuel using the heat from the compression of the cylinder, unlike a gasoline engine which uses spark plugs. Once you cash your rings you loose some of that compression which will make your engine hard, if not impossible, to start. Ether is MUCH more flammable than diesel so it makes it easier to start the engine. The more you use it though the more you will exasberate the problem. Doesnt hurt once and a while though.
Any good diesel is going to have glowplugs that help you start it in the cold.