Autolite Glow Plugs are designed for diesel engines. Diesel engines depend on high heat in the combustion chamber to ignite the fuel, and when you cold start a diesel engine, there isn't enough heat to get it going. When you turn the ignition switch, the glow plug warms the combustion chamber to start the fuel ignition. These glow plugs fit a variety of diesel applications. If you're experiencing problems starting your diesel engine, it may have burnt out glow plugs. For dependability and long-lasting performance, use Autolite Glow Plugs.