Must the engine oil be changed when only 10% remains?
3 Answers
Engine oil with only 10% remaining can be selectively replaced. The functions of engine oil include the following 3 points: 1. Lubrication: There is rapid relative sliding between the piston and cylinder, as well as between the main shaft and bearing bush. To prevent excessive wear of parts, an oil film needs to be established between the two sliding surfaces. A sufficiently thick oil film separates the surfaces of the relatively sliding parts, thereby achieving the goal of reducing wear; 2. Auxiliary cooling: Engine oil has a relatively low specific heat capacity and is located inside the engine, so it does not inherently have a cooling effect. However, during engine operation, heat energy is generated by fuel combustion. The engine oil can carry the heat back to the oil tank and then dissipate it into the air, assisting the radiator in cooling the engine. The actual cooling effect is provided by the water outside the engine casing; 3. Sealing and leak prevention: Engine oil can form a sealing ring between the piston ring and piston, reducing gas leakage and preventing the entry of external contaminants.
Seeing the engine oil level at only 10% is usually a warning signal on the car dashboard, and I believe it's time to take it seriously. The primary functions of engine oil are to lubricate engine components, reduce friction, and dissipate heat. If the oil quality deteriorates, it can lead to engine overheating or accelerated wear, significantly increasing the risk of failure. I once drove a car where a friend waited until it reached 0% to change the oil, and the engine overhaul ended up costing nearly ten thousand dollars—totally not worth it. Manufacturers generally recommend changing the oil when it's around 5% remaining, but 10% is a critical threshold. Taking action early can prevent major issues. Regular maintenance, such as changing the oil every 8,000 kilometers or so, helps maintain the car's performance and longevity. I always advise not to cut corners—safety first.
From an economic perspective, although having 10% oil remaining doesn't necessarily require immediate replacement, it's worth weighing the costs. Changing to new oil might cost a few hundred dollars, but if you continue driving until the oil fails, engine damage could cost thousands or even tens of thousands in repairs—a case of being penny-wise and pound-foolish. I've noticed most vehicle manuals recommend preparing for an oil change at 15-20%, with 10% already being a late-stage warning phase. For daily driving, it might be acceptable for short city trips over a week or two, but highway driving or heavy loads pose higher risks. Changing oil earlier actually saves money and hassle in the long run, as the savings on repair costs outweigh the time spent. In short, don't be penny-wise and pound-foolish—planning your maintenance schedule wisely is the best approach.
