Central Illinois diesel guy here. While we don't get and maintain the cold weather you do, we get "arctic blasts" that drop temps to -20 (-40 windchill) several times a year over the past few years. I so have a heated garage however my vehicles don't get to be stored in it. Too many toys.
So my primary daily driver is a diesel truck. I've also primarily driven older trucks and such over the years and have use most all winter time heaters for engines with the exception of magnetic oil heaters. Both my old gas truck and my diesel have similar setups. "Freeze plug" block heaters to heat the coolant makes the engine warm up faster but doesn't really effect the oil because its all sitting in the pan. But the warmer the block is to start with the faster it heats it up. I just run synthetic oil to compensate. Has been working for me that way for years and haven't had an issue at all.
Dipstick heaters are just a gimmick. I could see running a silicone pan heater but that oil in the pan won't warm up the block because unkess the pump is running it isn't circulating. Of course warmer oil is good for the engine however my trucks have never had an issue and they have A TON of miles and cold starts.
Battery warmers come in two flavors and I have both. Blankets on the diesel, pad on thr gaser. Blankets that wrap around or silicone pads that sit in the bottom of the tray. The blankets work better because they also block wind but are bulky and a bit of a pain when changing the battery due to the one size fits all aspect. Silicone pads are easier, and a trip to the junk yard can net a nice factory foam battery cover to make it just as good as the blanket.
