The boiling oil and stuff is definitely extreme. I have a few extreme fantasies that are internal with me....I might put them into a story sometime. I'd never seriously broach the ideas, even with a very adventurous sub.
That said, when I came of age sexually, there were a lot more pulp magazines out there. The ladies got titilated over "True Confessions," (often written by male grad students--I knew one). Then there were the "man's true adventures" mags. A pot-boiler story was the hapless girl(s) fallen into the hands of the Nazi butchers. The girls were French partisans, British or American spies, poor peasant girls, all had to be tortured for military purposes or just plan sadistic fun.
The artwork was fantastic! There are sites where the stuff is collected. One of my enduring images is the buxum dish with long blonde hair, wearing a full-skirted blue dress--[i]blowing up to her waist, displaying sexy lace-edged knickers[i/] as she's grabbed off the streets by a Nazi goon in the sidecar of a speeding motorcycle! The look of fear on her face, the cleavage of her tits displayed in the snug bodice, the skirt and petticoat blowing upward....very tame by today's standards, but it has been a virtual icon of bdsm for, well, generations.