07 / SAVJETODRŽAVANJE
2026-03-08 · ODRŽAVANJE

When to Change Oil, Filters, Brake Fluid, and Coolant

Oil, filter, and fluid replacement intervals for your vehicle. A practical guide to routine maintenance.

Routine maintenance is not complicated, but many drivers are unsure about what gets changed when. Manufacturers give their recommendations, but workshop experience sometimes tells a different story. Here are concrete intervals based on what we see every day.

Engine Oil

The standard interval is 10,000 to 15,000 km or once a year, whichever comes first. Some manufacturers specify 20,000 to 30,000 km, but that only holds true with high-quality long-life oils and ideal driving conditions.

In practice, if you drive short trips around town, sit in traffic, or have an older vehicle, you are better off changing at 10,000 km. City driving is harder on oil than most people think: the engine does not warm up enough, moisture accumulates in the oil, and it loses its protective properties faster.

Oil filter is always replaced together with the oil. There is no point in running fresh oil through an old filter.

Air Filter

The recommended interval is 20,000 to 30,000 km. The air filter can be checked visually: pull it out and look at it. If it is dark gray or black, it is time for a new one.

A clogged air filter means less air reaching the engine, which results in higher fuel consumption and weaker performance. On some cars, the difference in consumption can be as much as half a liter per 100 km.

Cabin Filter (Pollen Filter)

The replacement interval is 15,000 to 20,000 km or once a year. This filter cleans the air entering the cabin. When it clogs, heating and A/C work less effectively, windows are harder to defog, and there may be an unpleasant smell inside the car.

Many drivers forget about this filter because it does not affect engine performance, but it directly affects your comfort and health.

Coolant (Antifreeze)

Coolant should be replaced every 2 to 3 years, regardless of mileage. Over time, it loses its anti-corrosion properties and its ability to protect against freezing. Old coolant can cause corrosion inside the cooling system, leading to expensive repairs.

Between changes, check the level in the reservoir. It should sit between the min and max marks. If you notice the level dropping frequently, that points to a leak that needs to be found and fixed.

Brake Fluid

Replacement is recommended every 2 years. Brake fluid is hygroscopic, which means it absorbs moisture from the air. The more moisture it contains, the lower its boiling point. In a worst-case scenario, during heavy braking (such as descending a mountain road), the fluid can boil and the brakes temporarily stop working.

This is one of those items drivers routinely skip because "the brakes feel fine." That is exactly the point: they should feel fine even in a critical moment.

Spark Plugs

Standard spark plugs last 30,000 to 60,000 km, while iridium and platinum plugs can go 80,000 to 120,000 km. Worn spark plugs cause hard starting, rough engine operation, and higher fuel consumption.

On vehicles running LPG, spark plugs wear out faster because gas burns at a higher temperature. For those vehicles, we recommend checking plugs at 20,000 to 30,000 km.

Why You Should Not Blindly Follow the Service Book

Manufacturers sometimes specify longer intervals because it makes the total cost of ownership look lower on paper, which is a good selling point. But those intervals assume ideal conditions: quality fuel, a mild climate, and mostly highway driving.

Our conditions are different. Short city trips, dusty roads, summers hitting 40 degrees, and winters dropping to minus 15. That is why we recommend sticking to the more conservative intervals listed above.

Our Advice

Make yourself a simple table showing what was last changed and at what mileage. When you come in for service, we will show you what is due and what can wait. Sticking to these maintenance intervals is the cheapest investment you can make in your vehicle's longevity.

10 / KONTAKTPoziv na akciju

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Workshop address
Auto Gas Gaga
Njegoševa 44
Banja Luka, Republika Srpska
Bosnia and Herzegovina
Working hours
Mon-Fri08:00 - 17:00
Saturday08:00 - 13:00
SundayClosed
AUTO GAS GAGA · BANJA LUKA · OD 1996.
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