"It can wait a bit longer." We hear this all the time. The car runs, nothing is beeping, so why spend money on a service? I get that logic, but as someone who opens up engines every day, I need to tell you what is happening inside when you keep putting off a service.
What Happens to the Oil
Engine oil has a limited life inside the engine. It does not go bad from sitting around; it breaks down from working. At high temperatures, oil oxidises, loses its viscosity, and its ability to lubricate. The additives that protect against corrosion, clean the engine, and maintain seals all have a limited lifespan.
After 15,000 km (or one year), oil is already significantly degraded. After 20,000-25,000 km, on many engines it no longer provides adequate protection. And when we hear that someone has not changed their oil for 30,000 or 40,000 km, that is already in serious damage territory.
Sludge Build-Up
When oil loses its ability to hold contaminants in suspension, they settle out. That black, sticky sludge collects in oil passages, on the oil pump screen, and around the valve train. It gradually narrows the channels that oil flows through.
What this means in practice: The engine parts furthest from the oil pump (rocker arms, camshaft) start receiving less oil. Wear accelerates, and you do not hear or see it, until one day the engine starts knocking or the oil pressure warning light comes on.
We have seen engines at 150,000 km that look like they have 300,000 on them, simply because services were delayed.
Filters That Stop Filtering
The oil filter has a limited capacity. When it becomes saturated, a bypass valve opens and oil circulates unfiltered. That means metal shavings, soot, and other contaminants flow freely through the engine.
The air filter is a similar story. A clogged filter restricts airflow, the mixture runs too rich, and the engine burns more fuel. On diesel engines, this also puts extra strain on the DPF filter.
Accelerated Wear
An engine running on degraded oil wears out faster. It is simple physics: less lubrication means more friction, more friction means more heat and wear.
Real examples from our workshop:
A 1.9 TDI engine at 180,000 km with regular services: we opened the valve cover and the inside was clean, bright metal. The same engine, same mileage, irregular services: everything coated in black sludge, rocker arms scored, camshaft with visible wear marks.
Warranty and Resale Value
If your car is under warranty, a skipped service is grounds for denying a warranty claim. The manufacturer is clear: service on schedule or the warranty is void.
Even after the warranty expires, a service book with regular entries increases the car's value when you sell.
How Much Do You Actually Save by Delaying?
A basic oil change costs 80-150 KM depending on the car and the oil. An engine destroyed by poor maintenance costs 2,000-5,000 KM for a rebuild or replacement. The maths speaks for itself.
One skipped service probably will not destroy your engine. But the habit of delaying, servicing at 25,000 instead of 15,000, choosing cheap oil instead of the recommended grade, that adds up. The damage is not visible right away, but it is inevitable.
Our Recommendation
Change your oil at 15,000 km or once a year, whichever comes first. Do not wait for the indicator on the dashboard to tell you. It is set to factory intervals that are often overly optimistic.
Use quality synthetic oil in the specification your engine requires. The price difference between good and bad oil is 20-30 KM, but the difference for the engine is enormous.
If you have already fallen behind on services, it is not too late to start doing them regularly. Come by, and we will check the condition and put together a maintenance plan that suits your car and your budget.