I have tried Block Heaters, In radiator line heaters and then the Oil Pan heater.
Oil Pan is the best - it'll fire up like it was 60+ degrees out side when it is below zero!

My brother-n-law owns 2 Case backhoes and in the dead of winter (works super for clearing driveways) he's had to use one of them large propane torches along with a oil pan heater. He too found out block heaters don't work well!
The oil needs to be warm! I don't care how hot that water is, if that oil is cold it is like 90 weight! And roll overs in winter are hard on any diesel engine.
Infact the Worst thing you can do to a diesel is start it up!

My W115 240 1974 sat for over a year. Within 20-30 roll overs it fired up and died, and then refired and stayed running. The first die was my fault, I let off to quickly on the throttle.

Wanna know what can happen when using "Ether"? My brother-n-law shortly after buying his first 580C Case backhoe, one morning it wouldn't start, it was setting in a large Barn.
It wouldn't start so he shot it with ether, then again and once more and too much - POW! The Head blew off the block, tore off the sheet metal hood and kept going up, it hit the roof and then came back down landing in the hay mow!
My father-n-law, a good one for using lots of either. Blew the heads off a 3 cylinder snowmobile! He locked up a 230 Cummins so bad that even when pulled the rear tandems skidded.
Cummins have a release bolt for just that reason and it still took over a day to clear the ether from the intake and heads. Had to also relieve pressure from all 6 injectors!

Ever wonder what would happen if you filled a tank with gasoline that should have #2 diesel? Trust me, it ain't a pretty sight!
Brand New D3 Catapillar, the oil company filled the dozer with premium gasoline!
Jack didn't know it, he fired it up (winter) and let it warm up, while he did so, he sat in his warm Chevy pickup several yards away.
KahBlooie! There was only one piston and rod still in that 4 cylinder diesel engine when it was all done! Destroyed the engine, the hood, the radiator, part of the dash, most of the wiring.
The oil company had to buy a lot of very expensive new Catapillar parts!

If you ever run out of fuel Never try to restart it, the more times you do the worse it gets, yeah I found out the hard way!

A MB diesel engine will run on straight K1 kerosene. It will also run on JP4 (Jet Fuel) which is a highly filtered and refined Kerosene.
MB shows in their manual tells that you can reduce/cut the #2 with kerosene by up to 50% for harsh winter conditions. You can cut it with gasoline, but you had better know what you're doing when you use gasoline.

My brother filled up his Peogot diesel with kerosene, said it lacked power, but ran okay and smoked a bit more than normal. Said the mileage dropped some too. He was in a part of Maine where they'd ran out of #2 diesel and only had kerosene, so filled up and drove home.
I would imagine the Cetane rating of kerosene is pretty low. Maybe it is too high, don't know, anyone have a guess?