Getting the best engine performance means choosing the right glow plug, which depends on a number of different factors – the engine type, air–fuel mix, nitro percentage, and even air temperature.
What's more, the right glow plug will change as conditions change. Keeping a range of glow plugs on hand will help you fine–tune glow heat and enjoy maximum performance under all conditions.
Generally, hot plugs provide better idle and acceleration than cold plugs. Cold plugs will produce more power but may idle more roughly and be harder to tune.