What does it mean when a sedan 'boils over'?

[DiMargaret]

When a sedan 'boils over', it means the engine's operating temperature has risen beyond the normal working range, which can impair the machine's performance and cause damage. If you encounter a high-temperature warning, you should first reduce speed, then pull over to the side of the road. Do not rush to turn off the engine immediately, as excessively high temperatures can cause components like pistons, cylinder walls, cylinders, and crankshafts to overheat, thinning the engine oil and reducing its lubricating properties. Engine oil, or motor lubricant, serves two main functions: 1. To cushion the impact loads on pistons, piston pins, connecting rods, and crankshaft bearings; 2. To form a sealing ring between the piston rings and pistons, minimizing gas leakage and preventing contaminants from entering.