Chapter 17: Automobile Maintenance

1. Power system

The main conventional engine types are:

• Spark-ignition engine using gasoline as fuel
• Compression-ignition engine using diesel

Idle: Its function is to prevent the engine from stalling when not in gear. A high idle increases fuel consumption.

Air filter: A dirty filter can impair engine performance; inspect and replace it as specified, especially in dusty conditions.

Accelerator: Determines the amount of fuel, the more you accelerate the greater the consumption.

2. Electrical system

Lighting: Adjust the headlights, if poorly adjusted:

• If they are too high: it can cause glare for other vehicles.
• If they are too low: you will not see the road sufficiently.

Ignition: Gasoline engines use spark plugs; diesel engines ignite fuel through compression.

Charging circuit: Provides energy and recharges the battery.

In a conventional combustion vehicle, the alternator supplies electrical energy and recharges the battery while the engine runs. With the engine stopped, electrical equipment draws energy from the battery.

A battery stores energy chemically and supplies electrical power. For maintenance:

• Keep terminals clean, secure and protected from corrosion according to the manufacturer’s instructions.
• Add only distilled water, never sulfuric acid. For maintenance free batteries, you will never have to add anything
• If the engine will not start, it could be because the battery is empty or has exceeded its useful life

3. Lubrication system (oil)

Check the oil level with the vehicle on level ground and the engine stopped, using the dipstick or electronic display as instructed by the manufacturer. Keep it between the minimum and maximum marks.

Change the oil and filter at the manufacturer’s intervals, using the specified oil. Follow the safe servicing procedure; hot oil can cause burns.

If the red oil-pressure warning stays on with the engine running, stop safely and switch off the engine immediately. It may indicate low pressure, not just low oil level; check the level and obtain assistance before continuing if the fault persists.

4. Cooling system (water)

Coolant carries heat to the radiator, assisted by airflow and a fan. Check its level when cold and use the manufacturer’s specified coolant/antifreeze mixture, not plain water as the normal fill. Never open a pressurised coolant cap while hot. If the engine overheats or coolant leaks, stop safely and arrange assistance.

5. Steering system

Allows the driver to direct the movement of the vehicle to follow the desired path.

At low speed, the progressive power steering minimizes the effort required to move the steering wheel.

6. Suspension system

Responsible for maintaining the stability of the vehicle.

If the suspension is in poor condition, the rear of the vehicle will rise excessively when braking. It can also cause an oscillation of lights which can blind other drivers.

7. Transmission system

Automobiles are moved by the force of an engine, which is transmitted to the drive wheels.

The gearbox provides the appropriate gear ratio. Difficulty changing gears can indicate a clutch, gearbox or lubrication fault and should be checked by a workshop.

The clutch connects or disconnects the engine from the transmission. Pressing the clutch pedal disengages it and interrupts drive. If engine speed rises without a corresponding increase in road speed while the clutch is engaged, it may be slipping and needs inspection.

Vehicles may be:

• Front wheel drive: the front wheels are the drive wheels.
• Rear wheel drive: the rear wheels are the drive wheels.
• Four-wheel drive: all wheels are drive wheels (4x4).

Check the steering wheel when it becomes too stiff or too loose.

8. Maintenance

Keeping your vehicle well-maintained, especially tyres, brakes and lights, helps prevent accidents. Pass ITV inspections when due; an ITV pass does not replace regular maintenance.

Required equipment for Spanish-registered passenger cars includes:

• a spare wheel or temporary-use wheel with the necessary tools, or an adequate alternative tyre-repair system; follow its pressure, speed and distance limits
• a certified connected V-16 emergency warning beacon from the DGT’s published list; since 1 January 2026, triangles and non-connected beacons do not meet this requirement
• a high-visibility reflective vest within reach, worn by the driver when leaving the car and occupying an interurban carriageway or shoulder; a vest for each passenger is recommended

Check tyre pressures when cold, including the spare, and inspect tread and damage. Car tyres need at least 1.6mm in the main grooves. Check brake-fluid level and have unexplained losses investigated; do not just top up. Follow all manufacturer service intervals.

Fumes:

• White: brief vapour after a cold start can be condensation; persistent dense white smoke requires inspection.
• Bluish: burning oil.
• Black: poor engine tuning, dirty air filter, excess fuel in the mixture.