The ten-minute check that catches most car problems early

Expensive repairs almost always send a postcard first. A coolant level that is a little lower each month. A tire that needs air more often than the others. A bulb nobody noticed because it faces backward.

Ten minutes, once a month, catches most of that. Pick a fixed day so it actually happens — the first Sunday, or whenever you fill up for the second time. You need a tire pressure gauge, an old rag, a flashlight and nothing else.

Two ground rules. Fluid checks happen on level ground with the engine off and cool. And if a check in your handbook specifies different conditions, the handbook wins — a few cars want the transmission fluid checked warm and running, and some have no dipstick at all, only an electronic readout in the menus.

Tires: pressure first

Check them cold, meaning before you drive or after the car has sat for a few hours. Rolling heats the air inside and raises the reading, so pressures set at the end of a highway run will be low the next morning. The correct figures are on the placard in the driver's door jamb or inside the fuel flap, often with a second, higher set for a fully loaded car. The number molded into the sidewall is the tire's maximum, not your target.

Do the spare too, if you have one. It loses pressure sitting in the dark for years and is invariably discovered flat at the worst possible moment. If your car carries a sealant kit instead, the canister has an expiry date on it.

Then look at the rubber. Scan each tread for cuts, embedded stones and screws, and run a hand around the sidewall for bulges. Two specific responses matter here: a bulge means the tire comes out of service now, not at the weekend; and a nail or screw sitting in the tread should be left where it is, because it is currently the only thing keeping the air in. Drive gently to a tire shop, or have the car collected.

Oil, without the guesswork

1. Park on level ground and switch the engine off, then wait a few minutes for the oil to drain back into the sump
2. Pull the dipstick out, wipe it clean with the rag, and push it fully home again
3. Pull it out a second time and read it flat — the level should sit between the two marks
4. If it needs oil, add a small amount at a time and re-check between each one

Small amounts matter because overfilling causes its own problems, and the gap between the marks is usually less than a liter. Use the grade the handbook specifies rather than what is on the shelf; the wrong oil in a modern engine is not a neutral choice.

What you are checking is the level. Engines that use a little oil between services are not automatically faulty, but a level that falls steadily, or one that needs topping up far more often than it used to, is worth mentioning at your next visit. Leave verdicts about oil condition to the person who knows the car's history.

Coolant, from a safe distance

Look at the translucent expansion tank and find the minimum and maximum marks on its side. Cold, the level should sit between them. That is the whole check, and it should be done cold every time — a hot cooling system is pressurized well above the boiling point of water, and opening it releases scalding coolant and steam upward, into your face. There is no version of this that is worth rushing.

If the tank needs topping up more than very occasionally, you have a leak, and a cooling system that runs low will eventually cost you an engine. Use the coolant type your handbook names, since the different chemistries are not always compatible, and buy it pre-mixed unless you are confident about diluting concentrate correctly.

Brake fluid: look, do not top up

The brake fluid reservoir has marks on it as well, and this is the one check where the reflex to fill it up is wrong. As brake pads wear down, the caliper pistons sit further out and the system holds more fluid, so a slow fall in the reservoir often just means the pads are wearing normally. Topping it up hides that signal, and then overflows when new pads push the pistons back.

A level that has dropped noticeably, a puddle anywhere near a wheel, or a pedal that feels different in any way is a different matter entirely: do not drive it, and have it looked at where it stands. Brake hydraulics are not a system to experiment with.

Lights, wipers, glass

At dusk, park facing a shop window or a garage door and you can check most of the lights alone, including the brake lights, by watching the reflection. Otherwise recruit somebody for ninety seconds. Reversing lights and rear fog lights are the ones that go unnoticed for years.

Wipers that judder, streak or leave a fine mist need replacing; wiping the rubber edge with a damp cloth buys a couple of weeks at most. Top the washer bottle while you are there, and clean the inside of the windshield occasionally, which does more for night visibility than anything you can buy.

The walk, the look and the listen

• Look at the ground where the car normally sits — clear water dripping in summer is condensation from the air conditioning and is fine, but anything colored or oily is not
• Slide a sheet of cardboard underneath overnight if you suspect a drip; the color and position tell a mechanic a great deal, and a phone photo saves an hour of diagnosis
• Glance under the front for a hanging undertray or a dangling clip, which is common after a curb and cheap to refit
• Start the engine with the radio off and simply listen for ten seconds
• On the next drive, notice anything new when braking, turning at low speed, or going over a bump

Where the line is

Everything above is done standing up, with the car on its wheels. That is not a coincidence. Never get under a vehicle supported only by the jack that came with it — that jack exists to change a wheel at the roadside, on level ground, with nobody underneath. Working under a car needs proper stands on a hard, flat surface, and if that sentence makes you uneasy, it is telling you something useful.

Brakes, suspension, steering and airbags are all systems where fasteners have torque specifications for a reason, and where a mistake is not the kind you find out about gradually. Checking them is yours; adjusting or replacing them is a shop's.

Set a repeating reminder on your phone and keep the gauge, the rag and the flashlight in the trunk so the excuse never arrives. The whole routine takes less time than filling the tank.