Drivers are being urged to take better care of their engines – and it could be as simple as heading down the motorway now and then. Experts have warned that cautious, slow driving habits may actually be doing more harm than good, increasing the risk of engine damage caused by carbon build-up – often referred to by mechanics as “black death.”

Most motorists try to protect their cars by driving gently around town, but this can unintentionally lead to long-term problems. One of the biggest risks is the accumulation of carbon deposits, which clog internal components, reduce fuel efficiency, and can eventually lead to engine failure.

If you’re constantly driving at low speeds – especially for short journeys – your engine never gets hot enough to burn off carbon deposits. Over time, this can lead to a build-up inside your valves, pistons and exhaust system.

Known as “black death” because of its thick, dark appearance, the deposits are a by-product of unburnt fuel and poor engine circulation. Left unchecked, they can harden and cause serious damage.

In the worst-case scenario, carbon build-up can cause your engine to seize – and replacing that could cost thousands.

Thankfully, there’s a simple solution – and it doesn’t cost a penny.

Modern engines are designed to be run at higher speeds from time to time. Taking your car for a steady drive on the motorway helps heat the engine fully and allows fuel to clean and lubricate components.

Petrol, when forced through the system at higher pressure, can act as a natural solvent – cleaning valves and piston rings as it goes.

Another warning sign to look out for is white foam or froth under the oil cap, which could indicate water condensation in the engine oil, often caused by short trips where the engine doesn’t heat up properly.

If you take your oil cap off and notice a milky substance, that’s usually a sign your engine isn’t getting hot enough to burn off moisture. It’s not necessarily a serious fault, but it can lead to long-term problems if ignored.

Again, a regular long-distance drive at a steady speed can resolve the issue. When you drive at motorway speed for 45 minutes to an hour, the heat generated by the engine is enough to evaporate condensation and prevent that build-up. Keeping up with maintenance and using preventative measures like these can keep your vehicle in a better condition for longer, and hopefully save your bank balance from taking a big hit too.