“Why ‘Just One More Mile’ Before an Oil Change Could Cost You Dearly”

The Harmful Effects of Skipping Oil Changes

Automotive engine oil serves four primary functions: lubrication, cooling, cleaning, and rust prevention. During operation, hundreds of metal components within the engine move at high speeds and temperatures reaching hundreds of degrees Celsius. The thin oil layer between these surfaces reduces friction, prevents wear, and maintains performance.

Over time, especially in urban conditions with frequent stop-and-go traffic, the oil oxidizes, thickens, and loses its lubricating ability. Particulate matter, metal shavings, and contaminants from the combustion chamber mix with the oil, altering its viscosity. This causes the oil to become “heavier,” less flexible, and unable to protect metal surfaces effectively.

Delaying oil changes leaves the engine operating without adequate protection, a condition drivers may not immediately notice but accumulates damage over time. Continued operation with degraded oil forces components like bearings, piston rings, camshafts, crankshafts, and pistons to work under increased friction. This accelerates engine wear, reduces compression and power output.

Fuel consumption rises due to higher friction resistance. The engine runs hotter, causing the cooling fan to operate more frequently, increasing electrical drain and shortening battery life. Contaminated oil also forms carbon deposits and sludge in the engine block and oil cooler, clogging oil passages.

More critically, once the oil loses its lubricating properties, even a single cold start can cause dry friction between the camshaft and crankshaft for a few seconds, creating microscopic scratches that accumulate into significant damage over thousands of kilometers.

Engine Oil Has a Lifespan

Many drivers focus solely on the mileage displayed on their dashboard, rarely considering that engine oil also ages over time. Some believe that “if the car is parked and not driven, the engine isn’t working, so oil changes are less frequent.”

However, even when a vehicle is driven infrequently, oil still oxidizes due to heat, moisture, and the natural breakdown of additives. Manufacturers typically recommend oil changes every 6 months or after a specified mileage, whichever comes first.

Vehicles frequently used for short trips, with engines starting often but not reaching optimal operating temperatures, experience faster oil degradation. In such cases, oil can age prematurely even after only 5,000 km in 8 months.

Drivers can identify issues through familiar signs: a blinking or constantly illuminated oil warning light, increased engine noise or a slight knocking sound during acceleration, black or light blue exhaust smoke indicating oil burning in the combustion chamber, and oil on the dipstick appearing black, smelling burnt, or containing sludge.

When these symptoms appear, immediate oil and filter changes are necessary, along with checking for leaks or abnormal oil consumption.

Currently, oil change costs for standard vehicles range from 800,000 to 1,500,000 VND per service, depending on capacity and oil type. In contrast, engine overhaul due to severe wear or seizure from oil neglect can cost 20–50 million VND, or even require a new engine.

Therefore, timely oil changes are essential for extending an engine’s lifespan. Given Vietnam’s road conditions, hot and humid climate, and frequent traffic congestion, drivers should shorten oil change intervals compared to manufacturer recommendations, especially for urban or short-distance driving.

Delaying oil changes by a few hundred or thousand kilometers may seem minor but ranks among the top causes of premature engine wear, increased fuel consumption, and reduced longevity. A single timely oil change can keep the engine running smoother, more efficiently, and last for many years.