By Andy Smyth | July 2026
There’s an old saying among mechanics: a car’s engine is only as good as the maintenance it receives. After twenty-odd years of spannering, I can tell you it’s absolutely true. Engines don’t just fail out of the blue most of the time — they fail because something small got ignored somewhere down the line. Whether you’re driving a 1998 Ford Fiesta with 180,000 miles on the clock or a 2024 German saloon, the principles of keeping that powerplant alive are largely the same. It’s about consistency, knowing what to look for, and using the right materials for the job.
Let’s start with the absolute non-negotiable: oil. Your engine oil is the lifeblood of the whole system. It lubricates, it cleans, it cools, and it protects. Running an engine on old or incorrect oil is like trying to run a marathon in shoes two sizes too small — you’ll get a little way, but the damage builds up fast. There’s a lot of debate about the best approach, but I always point people toward a proper guide to the different types of motor oil and which one you should use. That single decision — picking the right viscosity and formulation for your engine — can make the difference between a motor that sails past 150,000 miles and one that starts rattling before it hits sixty. Check out the full guide to choosing the right oil at GMD UK .
Oil changes are straightforward, and they’re the single most impactful thing you can do for longevity. I recommend every 5,000 to 6,000 miles for conventional oil, and up to 8,000 for high-quality synthetics — though check your owner’s manual, because some modern engines have extended intervals. Change the filter every time, too. A clogged filter bypasses and sends unfiltered oil straight back into the galleries, which is worse than not changing the oil at all. It’s a ten-minute job that saves thousands in rebuild costs.
Next up: cooling. Overheating is the number one cause of terminal engine failure in Britain, especially in stop-start traffic on warm days. Your coolant level should be checked at least once a month. Look for the expansion tank — usually a translucent plastic bottle with min and max marks. If it’s low, top up with the correct spec for your vehicle. Never pour cold water into an overheated engine, though; you can crack the block. Let it cool naturally first, then investigate. Common culprits for overheating include perished hoses, a sticking thermostat, or a failed water pump. If you hear a whining noise from the front of the engine that changes with revs, water pump bearings could be on the way out.
Timing belts and chains are another area where neglect is costly. Most manufacturers recommend changing the timing belt between 60,000 and 100,000 miles. If it snaps, the pistons can hit the valves, and you’re looking at a rebuild or a replacement engine. Chains are generally more durable, but they stretch over time. A rattling noise from the front of the engine on start-up is a tell-tale sign the tensioner or chain needs attention. The cost of replacing a belt is a few hundred quid. The cost of ignoring it is a few thousand.
Let’s talk about spark plugs. Worn plugs cause misfires, rough idle, poor fuel economy, and eventually damage to the catalytic converter because unburnt fuel ends up in the exhaust. Modern platinum-tipped plugs can last up to 60,000 miles, but they should still be inspected periodically. If the electrode is rounded, the gap is too wide, or there’s heavy carbon buildup, replace them. It’s a simple job on most four-cylinder engines — just be careful not to overtighten, and use a torque wrench if you have one.
Air and fuel are the other two elements of the combustion triangle. A dirty air filter restricts airflow, making the engine run rich and guzzle petrol. Swap it annually or every 12,000 miles — it’s cheap and takes five minutes. Fuel filters are often forgotten, too. A clogged fuel filter starves the engine of fuel at high revs, causing hesitation and stalling. On most cars it’s an inexpensive part and a straightforward job, though some modern integrated filter-in-pump units are trickier.
PCV valves (positive crankcase ventilation) are a small component that causes big problems when blocked. They regulate pressure inside the crankcase, and if they clog, you can end up with oil leaks past gaskets and seals. It’s a ten-pound part and a two-minute swap on many engines — worth doing preventatively every couple of years.
Don’t forget the ancillaries: alternator, starter motor, and air conditioning compressor. These are driven by the auxiliary belt (often called the serpentine belt). Check it for cracks, glazing, or fraying every service. If it snaps, you lose the alternator, power steering, and water pump simultaneously. Most modern belts last 50,000–60,000 miles, but they’re cheap to replace early.
Listen to your engine. A healthy engine has a steady, rhythmic sound. If you hear tapping, knocking, hissing, or squealing, don’t turn the radio up — investigate. Tapping often means low oil pressure or worn hydraulic lifters. Knocking at the bottom end could be big-end bearing wear, which is serious. Hissing is usually a vacuum leak. Squealing is often a loose or worn belt. Your ears are one of the best diagnostic tools you have.
Routine checks are the backbone of engine longevity. Once a week, pop the bonnet and check the oil level, coolant level, brake fluid, and washer fluid. Look for any signs of leaks — fresh oil spots on the driveway, staining around the valve cover gasket, or a sweet smell that could mean coolant escaping. Catching a weep early means a gasket replacement; leaving it means towing costs and a much bigger bill.
A well-maintained engine doesn’t just last longer — it drives better, returns better fuel economy, holds its value, and is far less likely to leave you stranded on the hard shoulder of the M25 in the rain. The investment is time, mostly, and a modest amount on consumables. The return is tens of thousands of extra miles and the satisfaction of knowing your car is in proper mechanical shape.
If you’re just getting started with engine maintenance, pick one thing at a time. Learn to change your oil properly, then move on to coolant, then plugs. Build your knowledge step by step. And always use quality parts and the correct fluids — the couple of quid you save on cheap oil or a budget filter isn’t worth the potential damage. A good engine will look after you if you look after it.
