I remember pictures of lorry driver putting burning rages soaked in "something" under their lorry's fuel tanks in cold weather to get the diesel up to a better temperature
Apparently the cops "disapproved" for some reason!
When I was young, a day in winter used to start with holding a rolled up newspaper dipped in diesel and set alight into the air intake (with filter removed) of my Dad's Leyland to aid starting on a cold morning. Then run away to let the smoke clear as the engine warmed up, as you couldn't actually see the lorry any more due to the smoke. I honestly believe being around so many smokey diesel engines is why my Dad has serious respiratory problems now.
It was much the same with the tractors that we had.
A neighbour used to leave a small paraffin heater underneath his Ford D-Series on frosty nights! Not sure the health and safety people would approve.
Then he got a Hino and later Volvos that simply started easily in all weathers and weree warm and comfortable.