Glow plugs have a limited lifetime and users are advised to have several replacement plugs on hand. Replacement plugs must be the correct type; plugs for turbo engines are not compatible with plugs for standard engines. The plugs should be tightened a quarter-turn past a snug fit to avoid over-tightening. Glow plugs, like all incandescent objects, are extremely hot, and glow plugs should never be removed when hot. Likewise, care must be taken when fueling because a hot glow plug can ignite fuel. Overheating of the battery can also be dangerous and only well-made connectors should be used.