Back in the 80's I bought a brand new Ford Escort Mk 3 and drove it happily for over a year in the UK before tackling a continental trip. I fully serviced the car just before leaving home and traveled over 2K miles before returning home. Since I'd gone with a friend and my wife has stayed behind she had chosen to spend the time with my mother in her caravan at Cleethorpes. I drove the car there at quite reasonable
speeds both on the M180 and the A180. Half way along the 180 there was a loud BANG from the engine compartment and a little bump appeared in the bonnet. A spark plug had been ejected from cylinder 3! I soldiered on and returned home the following day with the car on the back of an RAC car transporter.On examining the car I found that the side electrode on every plug had completely eroded/burned away leaving the spark having to hop a gap tens of times the recommended gap. Piston 3 had a hole in the crown I could get the tip of my little finger through! I've returned to the continent on numerous occasions since, but I always keep a close eye on my spark plugs now.