How do I know when my car needs a service?

Servicing is one of the few areas where doing the cheapest thing consistently costs the most. The items that ruin engines are almost all on a schedule that nothing on the dashboard warns you about.

Step by step

1. Find your car's actual schedule.The handbook states the interval, usually as a mileage or a period in months, whichever comes first. The time limit matters for low-mileage cars, where oil degrades on age rather than distance.
2. Understand variable servicing if your car has it.Many modern cars calculate the interval from how they are driven and display a countdown. Short journeys and heavy loads bring it forward, which is the system doing its job.
3. Separate the service from the MOT.The MOT tests defined safety and emissions items on a single day. It says nothing about oil condition, filters, brake fluid, coolant or the timing belt. Passing an MOT is not evidence a car has been maintained.
4. Know which items are time-based.Brake fluid absorbs moisture and is typically changed every couple of years regardless of mileage. Coolant, cabin filters and, on many cars, the timing belt are all on time as well as distance.
5. Treat the timing belt as the big one.Where a car has a belt rather than a chain, it has a replacement interval in years and miles. A snapped belt usually destroys the engine, and it is by far the most expensive thing to forget.
6. Listen to the car between services.New noises, a change in braking feel, a warning light, a smell, or more oil use than usual. Any of those means a garage appointment rather than waiting for the next scheduled date.
7. Decide between a dealer and an independent.Independent garages can service to the manufacturer's schedule without affecting a warranty, provided the correct parts and oils are used and the work is recorded. On a car in warranty, check the terms.
8. Ask what is actually included.Interim, full and major services differ a great deal between garages. Ask for the list, and specifically whether brake fluid, spark plugs, filters and the cabin filter are included.
9. Keep the record properly.Stamps, invoices and a note of the mileage. Service history is worth real money at resale and it is the only proof that time-based items were done.
10. Plan for the expensive years.Timing belt, brake fluid, discs and pads, and a major service often fall close together. Knowing when they are due lets you save rather than be surprised.
11. Act on MOT advisories in between.They are a free forecast of what will need doing. Rolling them into the next service is usually cheaper than a separate visit.

Tips

• Photograph the service book each time it is stamped. Lost books cost money at resale.
• A car doing mostly short journeys works harder than the mileage suggests. Servicing on time rather than on mileage matters most for these.
• Ask the garage to keep any parts they replace. Reputable ones offer without being asked.

Common mistakes

• Treating the MOT as proof the car has been serviced — The MOT does not assess oil, filters, brake fluid, coolant or the timing belt. A car can pass an MOT the day before a timing belt failure destroys the engine.
• Skipping servicing on a low-mileage car — Oil degrades with time and moisture, brake fluid absorbs water, and belts age. A car doing three thousand miles a year still needs its time-based items on schedule.

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