A puddle under the car is read two ways: by colour, and by where it sits. Clear water near the front on a warm day, with the air conditioning running, is almost always condensation, and nothing is wrong. Anything green, orange, red, pink or oily is worth identifying before you drive far. Colour narrows it down fast, but it does not settle it, because several fluids now share the same colours.
Around Cheltenham and the bayside suburbs most cars park on concrete, so the stain is usually what gets noticed, not the leak.
The colour narrows it down. The position narrows it further. Neither of them proves it. Two well-regarded Australian motoring guides disagree about two of those rows. One puts green and orange on coolant, and red on the gearbox. The other allows green or blue to be brake fluid, and red to be the cooling system. A green liquid under the car was once shorthand for coolant. It is not any more, because long-life coolants come in blue, green or red.
Coolant is the row to take most seriously. A slow leak can show as little more than a damp patch near the front of the car, so it gets missed. How small car faults turn into big repair bills covers where that ends up.
| Colour and texture | Likely source | Where it usually shows | How urgent |
|---|---|---|---|
| Clear, watery, no smell | Air conditioning condensation | Front of the car, after a drive | Not a fault |
| Green or orange | Coolant | Front, under the radiator and hoses | Book it in promptly |
| Red or pink | Transmission fluid, power steering fluid, or coolant on a newer car | Further back for the gearbox, nearer the front for steering | Identify it before driving far |
| Brown or black, oily | Engine oil | Under the engine | Check the level, then book it in |
| Amber, oily, strong smell | Brake fluid | Near a wheel, or back of the engine bay | Stop if the pedal has changed |
| Blue | Long-life coolant, some brake fluids, or dyed screen wash | Front of the car, or a front corner | Treat it as coolant until identified |
Red or pink is the colour people look up by name, and a red puddle is not automatically the gearbox.
Automatic transmission fluid is generally a bright red, and it reaches the ground from a split cooler hose or the seal where a drive shaft leaves the gearbox. Power steering fluid is red too, and it tends to arrive suddenly rather than as a slow drip, because that system runs under pressure. On a newer car, red can be the cooling system.
Position does more work than colour here. Transmission fluid tends to show further back, under the middle of the car, and steering fluid nearer the front. Transmission servicing is a subject of its own, but a fresh red patch is an identification job first.
Usually, yes. Air conditioning takes moisture out of the air inside the car, and it drains onto the ground while the system runs. On a warm day that can be a respectable puddle with nothing wrong.
Three things tell it from coolant: no colour, no smell close up, and no oily feel between your fingers. It dries off concrete without a mark.
Losing refrigerant is different: the gas escapes without reaching the ground, so the sign to go by is that the air conditioning has stopped blowing cold.
The other clear one is screen wash, from a cracked bottle or a split hose. The additive in it is dyed, so that puddle can be anything from clear to a strong colour.
Most leaks can be driven gently to a workshop. An old oil leak on the driveway is a booking, not an emergency. Two are different.
Do not drive it if you think it is brake fluid and the pedal has changed. Brakes work on pressure in a sealed line, so fluid on the ground is pressure escaping. A brake fluid leak is the one case where the advice is to stop driving where the car stands.
Do not keep driving a car that is losing coolant and running hot. Heat is what turns a cheap cooling repair into an engine one.
Red is the one to identify before driving far. The published advice on a transmission fluid leak is not to drive on it until somebody has looked.
Two checks settle it in the driveway. How big is the patch after a night? A coin-sized mark is a weep, and something spreading is moving faster. Has the temperature gauge moved? Anything above where it normally sits, with a coloured puddle underneath, ends the decision.
You can narrow this down overnight, without tools and without going under the car.
Not every mark is a puddle. Shocks and struts are hydraulic too, so a film of oil down the body of one is that unit leaking, and it points at suspension repairs rather than an engine leak.
A leak gets traced, not guessed at. A cooling system can be put under pressure while the engine is cold, which pushes a weep into showing itself. That is ordinary cooling system leak detection, and it is a short job. A leak that only appears warm needs a dye in the system and a drive, then the source shows up under a lamp, which means two visits.
“We will keep an eye on it” is a fair answer for a weep that has not changed in months. It is not a fair answer for something dripping while the car is parked, or for anything in the brake or cooling systems.
One thing before any of that. Photograph the patch and leave the levels alone, because what went in the top is the first question anybody asks. The wrong top-up can make a cheap job a dear one: different coolants do not always mix, and some turn to gel. Take the photo, then book a time online with Chandos Auto.
Topping up hides the leak and the level drops again. The wrong product can also do damage.
That depends on the test. Pressure testing is quick and a dye test takes two visits.
One colour now covers more than one fluid, and red belongs to the gearbox, the steering and some cooling systems at once.
The quote came in higher than you think the car is worth, and now you have to decide. Comparing those two numbers is where the advice usually starts, and on its own it settles nothing. Here are the three numbers that do, written by the workshop that would be paid for the repair.
You reverse off the driveway and there is a stain on the concrete where the car was. Colour gets you most of the way to what it is, and where it sits under the car gets you the rest. Here is what each one usually means, which two are worth stopping for, and the cardboard trick that finds the source overnight.
You ring up to book a service and the first thing you are asked is which one you want. Nobody explains the question, so most people guess. The short answer is that a logbook service follows the list your manufacturer wrote, a standard service follows the workshop’s own, and which you need comes down mostly to whether the car is still under warranty.
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