Car Leaking Fluid? How to Tell What It Is by Color

A spot under your car can mean anything from completely normal to stop-driving-now. The good news is that each fluid has its own color, feel and smell, so you can usually tell what it is in a minute or two.

Slide a piece of white cardboard or paper under the car overnight. In the morning, the color of the drips and where they landed (front, middle, back, near a wheel) tell you most of what you need to know.

When to stop driving

Do not drive if you suspect a brake fluid leak (fluid near a wheel, a low brake reservoir, a soft brake pedal or the brake warning light), if you smell gasoline strongly, or if the coolant is leaking fast and the temperature gauge rises. Have the car towed or checked where it is.

Most common causes

Clear water: A/C condensation (normal)

Clear, odorless water dripping near the front passenger side after running the A/C is normal condensation. It evaporates and leaves no residue.

Green, orange, pink or yellow and sweet-smelling: coolant

Coolant (antifreeze) feels slightly slimy and smells sweet. It usually drips near the front of the car from the radiator, a hose or the water pump. Low coolant can lead to overheating.

Brown to black and slippery: engine oil

Engine oil is the most common leak. It usually drips under the engine, from the oil pan, drain plug, filter or a gasket. Small leaks are common on older cars, but keep the level topped up.

Red or pink and oily: transmission or power steering fluid

Red fluid near the middle of the car is often transmission fluid; near the front, it may be power steering fluid. Both need attention before the level gets low.

Light yellow to brown, slick, near a wheel: brake fluid

Brake fluid is thin and slippery and often shows up near a wheel or on the inside of a tire. This is the dangerous one: a brake fluid leak can make the brakes fail.

Blue, thin and watery: washer fluid

Blue (sometimes green or pink) watery fluid near the front is usually windshield washer fluid from a cracked reservoir or hose. Not a safety problem.

Strong gasoline smell: fuel leak

A gasoline smell, or thin fluid that evaporates quickly with a rainbow sheen, can be a fuel leak. Fuel leaks are a fire risk.

What you can safely check yourself

Put white cardboard under the engine and middle of the car overnight to see the color and location of the drips.
With the engine cold and the car on level ground, check the oil dipstick, coolant reservoir, brake fluid reservoir and (if your car has one) transmission dipstick.
Touch a drop with a paper towel: is it watery, oily, slimy or slick? Smell it: sweet (coolant), burnt (old transmission fluid), or gasoline?
Look at the inside of each tire and wheel for wet, oily streaks, which can point to a brake fluid leak.
Note how big the puddle is. A few drops overnight is different from a puddle the size of a dinner plate.

Step-by-step guides

Check your engine oil

Beginner · 2–5 minutes

When to call a mechanic

Have a shop find the source if the leak is anything other than A/C water or washer fluid, if you have to keep topping up a fluid, or if you are not sure what it is. Shops can clean the area and use dye to pinpoint the exact spot.

Frequently asked questions

Is it normal for water to drip from my car?

Yes, if it is clear, has no smell, and drips near the front passenger side after using the A/C. That is condensation and it is completely normal.

What color is a brake fluid leak?

Brake fluid is usually clear to light yellow when new and turns brown with age. It is thin and slick and often appears near a wheel. Do not drive if you suspect it.

Can I drive with an oil leak?

A slow drip is usually OK if you check the oil often and keep it topped up. A large leak, or an oil pressure light, means stop and get it fixed.

How can I tell if it is coolant or transmission fluid?

Coolant is watery-slimy and smells sweet; it is often green, orange, pink or yellow. Transmission fluid is oily, usually red or pink, and may smell burnt if it is old.