Being rediculously compulsive about my oiling, i too looked into an
oil warming system. I thought about the warming pad, but decided while they probably work well around a cylindrical dry sump tank, i doubt they can be attached tightly to an
oil sump, with all that wind and such down there. So i got a plug in
oil heater from Stef's, took my Avaid pan off, took it to a welding shop, the guy said he could weld in the threaded bung, so i then used my British concise hole punch, and popped a hole in the sump and left it for him to weld in. Came back, turned out i thought my sump was aluminum, but it is actually a shiny steel, so he couldn't weld my aluminum bung to it, (you can get a steel one), so he melted a corner of my sump trying, finally got a big NPT fitting welded in, but it was the wrong thread!!. so i just got a brass NPT plug, and there it sits to this day.
So, i bought a nice low heater fan, at a boating store, and when i anticipate driving the next morning ina cold temp, i just put the heater fan on low, push it under the motor, and it keeps my engine warm.
Many years ago, with my TR-4, which would not start much below freezing, and was living in Nebraska, i would set my alarm, and go out several times in the middle of the cold nights, start the engine, warm it up, and turn it off, and go back to bed, and do it again several times at night. Had a heated dipstick, once absently mindedly wiped it off with my fingers, and with the resulting burn, could not use my left hand for about a week until it healed.
Ah, the travial of a primative English motoring device.