Does Your Car Need Servicing If You Only Drive a Few Miles?

Low Mileage, No Problems? Why Your Car Still Needs Servicing

A common, genuine misconception is that if a car is used infrequently, surely it doesn't need servicing as often? In fact, cars should be serviced according to the manufacturer's service schedule - this can be by time interval or mileage, whichever comes first. Here we look at some common issues that arise with low-mileage usage and why regular servicing can help prevent these problems.

Engine oil ageing and contamination

Major engine oil brand Valvoline state unequivocally that low mileage driving, particularly short, stop-start trips, affect oil ageing and contamination. Insufficiently hot engine operating temperatures in such journeys fail to eliminate moisture build-up, acids form and consume protective additives in oil, and oil can be thinned by fuel which is not evaporated as it would be by longer trips, reducing lubricating properties. Online discussions may reflect differing views but their is a clear body of opinion among mechanics that the type of low-mileage driving is what matters, with, as mentioned above, short urban trips being much harder on engine oil. Best practice, therefore, may be to change oil more frequently or to take the car out for a longer drive at consistently higher speed (limits observed, of course) to get the engine up to temperature so condensation can be burned off.

Batteries losing charge when cars sit unused

It may seem odd that an unused car would lose charge, but there are negative effects to be encountered for car batteries in low mileage vehicles. Cars, even when parked, are using power for electrical components like alarms, computers and key systems. Infrequent driving does not give the alternator enough time to replenish this usage or the electricity used to start the engine when driven. With a partial charge, a batter is more likely to fail particularly in cold weather, and its capacity can be permanently reduced by lead sulfate crystal build up.

Brakes suffering from corrosion during periods of inactivity

Car brakes can suffer from corrosion and rust during periods of inactivity. This ranges from surface rust, which can occur quickly, through to deep pitting and corrosion. The later more extreme problems occur with prolonged effects of moisture, wear, humidity and road salt. In the most serious cases, rust can cause brake pads to adhere to rotors, or caliper pistons and slider pins to seize.

Tyres losing pressure and deteriorating with age

Even when stationary, tyres can deteriorate through natural degradation via exposire to oxygen, ozone, heat and UV light, making the tyres stiffer and less flexible with the potential to develop splits and cracks. Constant pressure through cars sitting for a prolonged period of time on the same spot can cause permanenent or semi-permanent depressions whic lead to vibration when the car is finally driven again. The RAC note that many manufacturers recommend annual inspection of tyres over 5 years old, regardlesss of wear or how much tread is left, and replacing any over 10 years old.

Moisture accumulating in the exhaust system

Leaving a car unused doesn't create moisture accumulation in the exhaust as such, but it does trap exhisting condensation - the natural byproduct of fuel burned by the engine. Regular usage will expel this moisture as steam with the heat from the engine and exhaust. Unused, the condensation cannot escape and may therefore cause corrosion from the inside of the exhaust outwards. This is another issue for the short, stop-start journeys previously mentioned as condensation can build up without the engine and exhaust reaching the necessary temperature to evaporate it.

Why short journeys can be harder on some components than longer trips

Short journeys can damage particular components in a number of ways. During a cold start, low oil temperature does not offer as much lubrication to moving parts and therefore increases wear on parts like pistions and cylinder walls. Repeated cold starts therefore exacerbate these issues. Oil contamination through water vapour occurs as the engine is never heated enough to evaporate water and sludge can build up, clogging oil passages. Batteries are drained more as insufficient charging time is available in a brief journey. Moisture build up in brakes and exhaust can lead to rust and decay, again due to inadequate exposure to effective running temperatures. Fuel consumption is also higher as the car uses extra fuel when it is cold, and does not reach an efficient running temperature either.

Diesel particulate filters (DPFs) and regeneration

Thinking about the emissions system, short journeys create very specific problems for catalytic converters, oxygen sensors and Diesel Particulate Filters (DPFs). In particular, the DPF is highly susceptible to problems caused by short trips. The DPF requires sustained journeys at higher speed and temperature whereby the build up of soot from diesel combustion, which the DPF traps for environmental cleanliness, is burned off in a process called regeneration. If the vehicle is not driven regularly in the required manner, soot can choke the exhaust sytem, blocking the DPF, ruining catalysts and firing up dashboard warning lights which can lead to a costly trip to the repair shop. Read our full article on Diesel particulate filters (DPFs) and regeneration for more information.

What if I need to leave my car unused for some time?

The AA offer some useful advice and tips on laying up a car in storage.  The key points are to clean and prepare the car first, top up fuel, check brakes, battery and tyres. There's also advice there for additional steps for storing a car for longer, and for getting back on the road after storage.

If your car is used for short trips only, or hasn't been driven for a while, don't worry! Book a service with the experts at Dowleys Garage and be assured by first-class advice and service. We'll be happy to explain any issues and make sure your car is safe and ready to use at all times.