To give you the most relevant information, could you tell me: Is this for a or an aircraft ?
Generally recommended when temperatures drop below 10°F–20°F (-12°C to -7°C). PREHEAT ENGINE
In diesel vehicles, a pigtail-shaped light indicates that the are heating the cylinder heads before starting, usually lasting 30 seconds or less. To give you the most relevant information, could
For electric heaters, it is often suggested to run them for 1–5 hours, though some keep them on overnight, say. though some keep them on overnight