Engine oil forms a lubricating film between the moving metal parts of the engine, carries away heat, keeps combustion residues in suspension and protects against corrosion. Over time the oil ages, loses its additives and becomes contaminated by soot and metal wear – then it can no longer protect the engine optimally. In an oil change the garage drains the old oil, replaces the oil filter, renews the drain plug seal and fills in exactly the specified amount and type of new oil.
The correct oil specification is crucial: the manufacturer precisely prescribes viscosity (e.g. 5W-30) and approval. The wrong oil can cause damage in modern engines with a particulate filter or long-life interval. The garage reads the specification from the vehicle data and documents the change, which is important for warranty and resale.
The change interval depends on the manufacturer and driving profile – typically every 15,000 to 30,000 km or once a year, whichever comes first. Many cars show a due change via the service indicator. Anyone who drives a lot of short trips should change towards the lower end of the interval, because the oil is more heavily stressed there. The oil change itself takes only about 30 to 60 minutes.
As a guideline (no guarantee): an oil change including oil, filter and labour costs roughly CHF 150–350 depending on the vehicle and oil type. Large engines with a lot of oil volume or expensive fully synthetic or long-life oils are higher. The oil change is often part of a small or major service, but can also be done on its own.