Why is engine oil referred to as the blood of an engine?

[OCora]

Engine oil is referred to as the blood of an engine because it performs functions such as lubrication, cleaning, cooling, sealing, friction reduction, rust prevention, and corrosion protection for the engine. The specific roles of engine oil include: 1. Shock absorption and buffering: When the pressure in the engine cylinder rises sharply, suddenly increasing the load on the piston, piston skirt, connecting rod, and crankshaft bearings, this load is transmitted and lubricated through the bearings, cushioning the impact load. 2. Rust and corrosion prevention: The lubricating oil adheres to the surface of parts, preventing contact with water, air, acidic substances, and harmful gases. 3. Lubrication and friction reduction: There is rapid relative sliding between the piston and cylinder, as well as between the main shaft and bearing shells. To prevent excessive wear, an oil film of sufficient thickness is established between the sliding surfaces, separating the parts and reducing wear. 4. Cooling: Engine oil carries heat back to the oil tank and dissipates it into the air, assisting the radiator in cooling the engine.

[LilyLee]

I think calling engine oil the 'blood of the engine' is particularly vivid—just like how humans can't live without blood. Last year, my friend forgot to change the oil, and the engine seized up and was completely ruined. Engine oil performs three major tasks in the engine: First, it acts as a lubricant, preventing the pistons and cylinder walls from grinding against each other—otherwise, it would be like sandpaper rubbing against metal. Second, it works as a cleaner, flushing carbon deposits and debris into the oil pan. Third, it serves as an air conditioner, carrying away 40% of the heat generated by friction. The golden flow of full synthetic oil is truly similar to how blood delivers nutrients. Remember to change it every 8,000 kilometers—thickened, blackened oil can't protect a precision turbocharger.

[EleanorDella]

Have you noticed that 4S shops always put engine oil in the spotlight? It directly determines whether an engine can last 300,000 km or just 100,000 km. Just like blood sustains human body functions, engine oil must simultaneously accomplish three tasks: lubrication, rust prevention, and sealing. High-speed friction between metal parts generates debris, which is filtered out by the oil filter acting like kidneys. Older vehicles especially require the right viscosity—0W-20 offers the best fluidity in northern winters when cold starts cause the most engine wear. Last time I used the wrong oil, my fuel consumption spiked by 2 percentage points.

[Dave]

After a decade of repairing cars, opening the oil pan tells the story. Engines using low-quality oil are covered in asphalt-like sludge inside, while those with regular full-synthetic oil changes still have a metallic sheen. This metallic blood network penetrates every crevice of the crankshaft and camshaft, with a 0.01mm oil film bearing tons of pressure. The most critical moment is when the oil pump fails—within five seconds of the dashboard warning light turning red, the bearing shells can melt and fuse, requiring a major overhaul. Performance car enthusiasts, remember to check oil levels before racing; insufficient oil pressure at high RPMs will definitely cause engine seizure.