An oil change is the most basic – and most important – piece of engine maintenance. How often should you do it, which oil should you choose and what happens if you skip it? This guide answers the questions drivers search for most and shows you how to check the oil yourself.
Why engine oil matters
Engine oil lubricates moving parts, carries away heat, protects against corrosion and carries fine particles and soot to the oil filter. Over time and mileage it ages: it loses lubricating properties, gets diluted with fuel and collects dirt and acids. Old oil no longer protects well, accelerating wear on the turbocharger, bearings and timing chain or belt.
How often should you change the oil?
The manufacturer’s interval is what counts – you will find it in the service book or on the car’s service indicator. As a rough guide:
- older cars and fixed service intervals: often every 10,000–15,000 km or once a year,
- newer cars with a “long life” interval: up to 30,000 km or two years, but only with oil of the correct specification,
- in any case at least every one or two years, even if you drive little – oil ages even while the car stands.
Many mechanics recommend a shorter interval for “severe conditions”: lots of short city trips, frequent cold starts, towing, dusty roads or sporty driving. On short trips the engine never fully warms up, so condensation and fuel accumulate in the oil.
Which oil should you choose?
Don’t choose by viscosity (e.g. 5W-30) alone. Even more important is the manufacturer’s specification or approval listed in the owner’s manual – such as an ACEA rating or the carmaker’s own standard. The wrong oil can harm a diesel particulate filter, and an extended interval is not safe without the right oil.
The first viscosity number (e.g. 0W or 5W) shows how fluid the oil is at a cold start – lower means easier starting in winter. The second (30, 40) describes viscosity at operating temperature.
Always change the oil filter too
Every oil change should include a new oil filter. The old one is full of dirt that would immediately contaminate the fresh oil. Depending on the interval, the air, cabin and fuel filters are often checked or replaced at the same service.
How to check your oil level
- Park on level ground with the engine off for a few minutes.
- Pull out the dipstick, wipe it and push it fully back in.
- Pull it out again – the level should be between MIN and MAX.
- If it is low, top up with oil of the same specification, a little at a time.
Some newer cars have no dipstick and show the level on the display. Check the oil every few weeks and before a long trip. Engines use some oil in normal operation, but a sudden increase in consumption is a sign the car needs checking.
Signs an oil change is urgent
- a red oil pressure warning light – stop immediately and switch off the engine,
- the service indicator shows the service is overdue,
- the oil is very dark and thick or smells of fuel,
- the engine is noisier than usual.
What happens if you skip an oil change?
One slightly late change rarely causes immediate damage, but regularly skipping changes shortens the life of the engine and turbo. Damage from poor lubrication is among the most expensive repairs. Missed services can also affect the warranty and resale value – buyers like to see a complete service history.
Find a garage near you
An oil change is part of the routine maintenance covered in our car service and maintenance guide. Kardet lists car service garages across Europe – send a free request with your make, model and mileage.