Engine Oil Change

The engine oil change is the most fundamental service operation. The oil lubricates the moving parts, prevents overheating and stops the engine seizing. A poorly lubricated engine suffers accelerated wear that can go as far as irreversible failure.

When should you change the oil?

The oil change is part of the service schedule set by the manufacturer. It must be done by a distance or time interval (whichever comes first). As a general rule: every year or every two years, and every 20,000 to 30,000 km. In severe use (short trips, town driving, repeated cold starts), the interval should be shortened.

Most recent vehicles have a service indicator that shows the distance or time left before the next oil change. Some systems even measure the oil quality to adapt the interval.

Why is the oil change essential?

The oil sits between the engine's moving parts (crankshaft, camshaft, valves, turbo, conrods, pistons). It reduces friction and prevents overheating and seizure. Over time it absorbs the by-products of combustion (unburnt hydrocarbons, soot) and picks up tiny metal particles. It then loses its lubricating properties and clogs the oil filter.

Should the oil filter be changed at every oil change?

It is strongly advised to change the filter at the same time as the oil. The filter holds a fair amount of used oil. If it clogs, the oil is diverted via a bypass and circulates unfiltered, accelerating engine wear and potentially causing irreversible damage.

Understanding oil specifications

SAE rating (viscosity)

Grades oils by their cold and hot ratings (e.g. 5W40). The first number indicates the fluidity when cold (the lower it is, the easier the cold start). The "W" stands for "winter". The second number indicates the resistance to heat.

ACEA rating (performance)

Classifies oils by letter and number. A/B = high ash content (engines without a DPF). C = low ash content (engines with a particulate filter). The grades A3/B4, A5/B5 and C1 to C5 indicate increasing levels of performance.

Oil families

Mineral oil: from refining crude oil, suited to older engines. Fully synthetic oil: produced by chemical synthesis, offering the best performance. Semi-synthetic: a blend of the two, a good quality/price compromise.

Types of sump plug

Tools for the oil filter

Oil-change steps