Interim vs Full Service: Which One Does My Car Need?

The quick answer

Most cars need a full service once a year. An interim service is a lighter check, usually around every six months or 6,000 miles, for drivers who cover a lot of miles, make lots of short trips, or tow. If you drive average mileage, a full service every 12 months or 12,000 miles is normally enough. If you do high mileage, add an interim service halfway between.

Your manufacturer schedule always comes first, so check your handbook or service book as well.

What an interim service covers

An interim service is built around the oil. The engine oil and oil filter are changed, fluid levels are checked and topped up, and the main safety items get a visual check, including tyres, lights, wipers, brakes and the battery.

Think of it as keeping the engine topped up with fresh oil and catching obvious problems early. It does not usually include replacing other filters or the more detailed inspections of a full service.

Because it takes less time and uses fewer parts, an interim service costs less than a full service. It is not a replacement for the yearly full service, though. Doing only interim services year after year means filters and other items that are due can be missed.

What a full service covers

A full service includes everything in an interim service and goes further. Alongside the oil and filter, the air filter is normally replaced and the cabin or pollen filter is checked or replaced depending on your car. The brakes, steering, suspension, exhaust, drive belts and hoses are inspected in more detail, and the car is road tested.

Some items, such as spark plugs, fuel filters, brake fluid and timing belts, are due at set mileages or ages rather than every year. Those are added when your manufacturer schedule says they are due, which is why it helps to have your service history to hand.

Some garages also offer a major service, which adds more of these longer-interval items. Whatever it is called, the important thing is that everything your manufacturer lists as due at that mileage gets done.

When an interim service makes sense

An interim service is worth it if you cover well over 12,000 miles a year, such as delivery drivers, sales reps and long commuters. Oil does not last forever, and at high mileage it breaks down well before the yearly service comes round.

It also makes sense if most of your driving is short trips, stop-start town traffic or towing. These are hard on engine oil because the engine rarely gets fully warm and moisture and fuel can build up in the oil.

If your car is getting older and you want to keep an eye on it, a check between full services is a sensible way to catch worn parts before they fail.

Variable service intervals on newer cars

Many newer cars use a variable or long-life service schedule. Instead of a fixed six or 12 months, the car works out when the next service is due from how it has been driven and shows a reminder on the dashboard. On some models that can be a long gap between services.

Those intervals assume the car is using the exact oil specification the manufacturer requires. If you do lots of short trips, some manufacturers recommend a fixed schedule instead, so it is worth checking which one suits the way you drive.

Whichever schedule your car follows, get the service recorded in the service book or the digital service record. A complete history helps protect your warranty on newer cars and makes the car easier to sell later.

Which one to book

A simple rule of thumb: if the dashboard service reminder is on, or it has been a year since the last full service, book a full service. If your car has not been serviced for over a year, or you do not know when it was last done, book a full service. If you had a full service recently and have already done a lot of miles since, an interim service is the right choice. If you are unsure, we can look at your service history and mileage and tell you honestly which one your car needs.

At MF Autocentre in Walsall we follow the schedule for your make and model and explain anything we find before doing extra work. Call us on 01922 636820 or book your service online.