What happens if engine oil is not changed on time?

[Braxton]

Not changing the engine oil on time will accelerate engine wear and affect engine performance. The steps to change engine oil are: 1. Lift the car, remove the protective plate, and place a container of about 10 liters under the oil drain screw; 2. Unscrew the oil drain screw, use an air gun to blow for two minutes at the oil filler port, after draining, tighten the oil drain screw and wipe it with a tissue to check for oil leakage; 3. Install the protective plate and lower the car, use a funnel to align with the oil filler port to add engine oil. The functions of engine oil are: lubrication and anti-wear, auxiliary cooling, cleaning, sealing and leak prevention, rust and corrosion prevention, and shock absorption. The types of engine oil are mineral oil, semi-synthetic oil, and fully synthetic oil.

[VanLandon]

I used to think it was fine to delay oil changes until my engine suddenly made a loud noise on the highway. Experienced drivers know that oxidized oil loses its lubricating effectiveness, causing engine parts to grind dry and potentially leading to cylinder scoring. Overused oil can even turn into a sticky sludge, clogging oil passages—I've seen engines with half a finger's thickness of black deposits inside. Not to mention the acidic corrosion of precision components. My repair bill was over 8,000 RMB—a painful lesson: regular oil changes are far cheaper than engine repairs!

[LeilaMarie]

Auto repair shops have seen too many car owners taking chances, so here's a special reminder: When the engine oil detergent is depleted, impurities will form hard deposits that clog the filter. Last week, a Golf came in with over 15,000 kilometers on unchanged oil—the drained oil was as thick as asphalt. The oil pump had to work overtime to push this 'waste oil,' directly causing hydraulic lifter noise and even scoring the camshaft. Now, replacing the entire engine costs as much as three years' worth of full synthetic oil!

[BrantleyRose]

Honest Talk from a Female Perspective: Last time I forgot to do the maintenance on time, I was terrified when I smelled a burning odor with the AC on. The mechanic said the overdue oil had turned into 'shoddy goods,' and under high temperatures, the oil film was as thin as paper, failing to protect the piston rings from scratching the cylinder walls. The scariest part was the sludge formation, which was like concrete, clogging even the oil pan pressure relief valve. Now, whenever the dashboard prompts an oil change, I book an appointment immediately—after all, I don’t want a second shock from the repair bill.

[StHazel]

Modified Car Enthusiasts' Real-World Warning! Aggressive Driving Demands Precise Oil Change Intervals. After just three laps on track day, the oil pressure warning light came on, and the diagnostic tool showed a surge in metal debris. Aged oil's shear resistance dropped to zero, causing crankshaft bearing clearance to widen and oil pressure to plummet. Even worse, the GPF got clogged, and replacing the catalytic converter cost as much as a set of coilover suspension. Now, changing to racing-grade oil every 5,000 kilometers is mandatory, saving at least a six-figure modification budget.

[LeilaniAnn]

Uncle Wang's lesson is worth sharing: his old LaCrosse went three years without an oil change until blue smoke from the exhaust pipe startled him. Upon disassembly, the sight took their breath away—sludge had wrapped the oil pump screen like a zongzi, and the bearing shells were worn down to bare copper. The crankshaft needed regrinding, and the connecting rod bearings required a full replacement. The most heartbreaking part was that even after the overhaul, fuel consumption remained two liters higher than when the car was new, making it unsellable even as a used car. Now, he sets two oil change reminders on his phone every month, more punctual than taking medicine.