I had to order a block heater on my 1985 Chev S-10 pick-up in 85 when I ordered it new..$60...also had to order a bumper and passenger side sun visor
..thats how bare bones trucks where back then..nowadays I think you have to order a fleet in order to get barebones and even then they come with an AM-FM radio.Back to a block heater in the frost plug nearest the first cylinder of firing oder (usually).I would like to know the difference in piston cylinder wall diameter on various types of blocks ie. cast iron,alloy etc. when 70 degrees as compared to -30 degrees...this contraction has to play a major role on all engine componants at start-up.The oil heater wouldn't play a major role in this arena.I think a tank type or frost plug coolant type would warm up the head,cylinder in the crucial area of first combustion start-up and a good synthetic oil would carry on (heated would be better)..