Otto Explains — Car Servicing
What Is a Major Car Service, and What’s Included?
Short Answer
A major service is the more thorough service that falls due at your manufacturer’s longer intervals: it covers the routine oil, filter and checks plus items replaced less often, such as spark plugs, filters, brake fluid, coolant and belts, depending on the vehicle. There is no universal list or mileage. What is due, and when, comes from your car’s own service schedule, and many manufacturers set a separate severe-usage schedule for conditions such as dust, short trips and heavy traffic.
What makes a service “major”?
There is no single industry definition. Garages often split servicing into an interim and a full service, sometimes called minor and major, and what each one includes varies from workshop to workshop. The reliable reference is the manufacturer’s schedule: it says which parts and fluids are due at each stage, depending on the model, its mileage and its age. In practice, a major service is the stage at which the longer-interval items fall due alongside the routine oil, filter and checks.
Which items does a major service usually cover?
A manufacturer’s schedule separates items that are replaced from items that are inspected. Replacement items typically include the engine oil and filter, the engine air filter, the cabin air filter, spark plugs, brake fluid and coolant, each on its own interval. Inspection items typically include the drive belts, brake discs and pads, brake lines, suspension, steering, exhaust and cooling system. Which of these fall due at a given service depends on your vehicle, so two cars can need quite different major services.
Why are filters and spark plugs replaced?
The engine air filter keeps dust out of the engine. As it clogs, fuel consumption rises, performance drops and, in time, engine wear increases, which is why it is replaced on schedule, and sooner in very dusty use. The cabin air filter stands between the pollutants in incoming air and the people inside, and stops dirt building up in the AC and heating systems. Spark plugs ignite the air and fuel in a petrol engine: worn plugs can cause misfires, loss of power, higher fuel consumption and a warning light. Long-life platinum or iridium plugs are replaced less often, and your service book gives the interval.
Why do brake fluid and coolant need changing?
Brake fluid absorbs moisture from the air over time, and the water lowers its boiling temperature: a brake supplier puts the drop at up to 80 °C in a year. Pedal travel can then become dangerously long and braking less effective, so brake fluid is replaced on the manufacturer’s recommendation, by age rather than mileage alone. Coolant also ages: its protective additives are used up, which allows corrosion, rust and scale that can damage parts such as the water pump. Coolants use different chemistries that don’t mix safely, so the replacement should be the type your owner’s manual specifies.
How are belts handled in a major service?
Some engines have a timing belt. It must be replaced at the interval the vehicle or belt manufacturer specifies, because a belt that fails can cause catastrophic engine damage, and a belt maker recommends replacing a timing-belt-driven water pump at the same time. The drive belt is usually inspected rather than replaced on a fixed basis. Modern drive belts resist cracking, so a technician looks for material worn from the ribs rather than counting cracks, and a worn belt can slip.
Does driving in Oman change what is due?
It can. Manufacturers publish a severe-usage schedule for conditions such as repeated short trips, long idling or low-speed driving, dusty or unpaved roads, heavy traffic, stop-and-go driving and towing. If any of them apply to how you use your car, the owner’s manual tells you to follow that schedule, which replaces items such as the engine air filter, spark plugs and cabin filter more often, and inspects the brakes, suspension and steering more often. Dust, traffic and idling are familiar to many drivers in Oman, but whether your car needs the severe schedule depends on how it is actually driven. For the oil itself, see how often to change your oil in Oman.
What does a major service at AutoTronix Express include?
The AutoTronix Express major service lists all periodic maintenance items (oil, filters and spark plugs), the condition of the brake pads, discs and brake fluid, a visual inspection of the suspension and steering, the fluid replacements due under the major service schedule, the battery and charging system, drive belts and hoses, lights and electrical safety items, and a review of the service history with recommendations for any further work. The scope is confirmed from the manufacturer’s schedule for your vehicle. Some of these items have their own Otto articles, such as when brake pads need replacing and checking transmission fluid.
Common Questions
- Is a major service the same at every garage? No. There is no standard definition, and what garages include varies. Ask for the list of items and compare it with your manufacturer’s schedule for your car’s mileage and age.
- Does a major service replace everything? No. Many items are inspected and replaced only when the schedule or their condition calls for it. A drive belt, for example, is checked for wear rather than changed at every major service.
- Why change brake fluid if the level looks fine? Because the fluid absorbs moisture over time, which lowers its boiling temperature and can make braking less effective. The level can look correct while the fluid has aged, so it is replaced on the manufacturer’s time-based recommendation.
- Can I mix different coolants when topping up? It isn’t a good idea. Coolants use different chemistries, and mixing incompatible types can cause corrosion in the cooling system. Use the coolant type your owner’s manual specifies.