Before trying to start a cold diesel engine, make sure that the battery is completely charged, and turn off all devices that use a lot of power, including the radio, air conditioner and heater. Obtain glow plugs or block heaters, and use them when starting the engine in cold weather to ensure that the motor starts easily and that the plugs and cylinder heads remain undamaged by cold fuel.
Glow plugs raise the temperature in the internal combustion chamber area to make the combustion possible. Using number 1 diesel fuel can help the engine to start easier in cold weather. It is better to keep the fuel tank full all the time in cold weather to prevent fuel from condensation, as it can plug fuel lines that go from the tank to the engine. Adding winter diesel fuel additive prevents the fuel from gelling, which makes it easier to start the engine.
It can be much easier to start an engine in a temperature that is just a few degrees higher than the temperature outside, so try storing the car or tractor in a garage or shed. Use a block heater with a timer if you are storing the machine outside, and set the heater to start working a few hours before you are going to start the engine.