Engine maintenance isn't always as simple as it looks — especially with so much outdated advice still circulating. Many drivers hold well-intentioned but incorrect beliefs about when and why their oil needs changing. Below, we tackle six of the most persistent myths, so you can keep your vehicle at its best based on facts rather than folklore.
Myth vs. reality
Myth 1: "You must change your oil every 5,000 km"
Probably the most stubborn myth in motoring. It was a golden rule decades ago, but engine technology and oil formulations have come a long way. Most modern engines, running on the manufacturer's recommended oil, are designed for much longer intervals — typically somewhere between roughly 10,000 and 30,000 km depending on the vehicle. Always check your handbook rather than an old rule of thumb.
Myth 2: "Dark oil means it's time for a change"
Many drivers pull the dipstick, see dark brown or black oil and conclude it's "dirty." In reality, darkening oil is often proof the fluid is doing its job: modern oils contain detergents that capture contaminants and keep them from forming deposits on engine parts. Colour is a poor indicator — the manufacturer's service interval or a professional oil analysis is far more reliable.
Myth 3: "Low mileage means no oil change needed"
A car that mostly sits in the garage still needs fresh oil. Oil degrades over time through oxidation and moisture build-up, even when the engine isn't running. This is especially relevant for hybrid drivers who lean heavily on electric power. Best practice: change the oil at least once a year, regardless of whether you've reached the mileage limit.
Myth 4: "Topping up is as good as a full change"
If your level is low, topping up is essential — but it's no substitute for a service. Fresh oil poured on top merely dilutes the old, degraded fluid; it doesn't remove the sludge and metal particles settled at the bottom. Only a full drain and refill properly protects your engine.
Myth 5: "The oil light is just a service reminder"
A dangerous assumption. When the oil warning light comes on, it usually signals a critical drop in oil pressure — not merely that the oil is "old." Pull over safely, switch off the engine immediately and check both the oil level and its condition. When in doubt, head to your local workshop.
Myth 6: "A fresh oil change means 100% new oil"
Unless an engine is flushed several times with fresh oil, roughly 10 to 15 percent of the old oil stays behind in galleries and on internal components. That share rises considerably if the oil filter isn't replaced at the same time — which is exactly why a new filter belongs in every proper oil change.
The facts in short
- Follow your manufacturer's service interval — not decades-old rules of thumb
- Judge oil by data (intervals, analysis), not by its colour
- Change oil at least yearly, even at low mileage
- Top-ups keep the level right, but only a full change removes contamination
- Treat the oil warning light as urgent, and replace the filter with every oil change
