My Ford solenoid has been in service for ~22k miles. I do carry a spare as previous experience with Ford vehicles has shown this to be good practice, but I've never needed it. During the winter, for that 5am first start of the day, I may glow for 40+ seconds and I've also just plain forgotten and left it on for several minutes more than once. So far so good.

I wonder if the much reduced amp draw of the glow plugs vs. a starter on a big V8 contributes to longer life.

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617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap