What is this fluid leaking under my car?
The short answer
Check the color: clear water under the A/C is normal. Brown-to-black is engine oil, red-pink is transmission or power-steering fluid, orange-green-pink and sweet-smelling is coolant, and clear-to-brown near a wheel is brake fluid — that one means stop driving. A photo of the puddle and the spot it came from tells us most of the story before you even arrive.
Reviewed by Joe Zeiter
Service Director · Grote service team · Updated July 17, 2026
Likely causes, ranked
A/C condensation (harmless)
Pure water dripping under the passenger footwell area after running the air conditioning is the system working correctly. If it’s water, wipe it — if it has color or smell, keep reading.
Engine oil seep — gasket or seal
Valve-cover gaskets, oil-pan gaskets, and crank seals harden with age and let oil weep, then drip. Brown to black, slick, usually toward the front half of the car. Rate matters: a damp film is a monitor item; fresh drops every night are not.
Coolant leak — hose, radiator, or water pump
Bright orange, green, or pink with a sweet smell. Coolant loss is self-accelerating — less coolant means more heat means more pressure on the next-weakest part. Worth a pressure test the same week you spot it.
Brake or transmission fluid
Brake fluid (clear to brown, near a wheel or the firewall) is a stop-driving finding — the pedal can go to the floor without warning. Red transmission fluid dripping means the level is falling toward the slip-and-burn zone.
What to do right now
- 1
Slide cardboard under the car overnight — position and color narrow the diagnosis dramatically.
- 2
Photograph the puddle and, if you can see it, the wet component. Text-worthy evidence beats a description every time.
- 3
Check the relevant dipstick or reservoir if accessible. Low brake fluid: stop driving and call us — (779) 888-5000. Anything else: drive gently and get it looked at within days, not weeks.
What it typically costs
Valve-cover gaskets commonly $150–$400. Coolant hoses $120–$300; radiators $600–$1,200. Power-steering and transmission lines vary widely, quoted after inspection. The free leak identification with any visit means you never pay to find out what the puddle is.
Our diagnosis fee goes toward the repair.
Related questions
Is it safe to drive with a small oil leak?
Usually, short-term — if you check the level weekly and it holds between top-offs. The risk isn’t the drip; it’s the day the seep becomes a stream on a part you can’t see. We measure the rate and tell you honestly whether it’s a fix-now or a monitor-and-watch.
The puddle is only there some mornings. Why?
Temperature. Gaskets contract overnight, and some leaks only open when parts cool. Intermittent puddles still identify themselves by color and position — the cardboard trick works precisely because of this pattern.
Can you find a leak I can’t see?
Yes — UV dye and a pressure test find the leaks that hide behind covers and shields. That’s part of standard diagnosis, and photos of what we find come with the quote.
What actually fixes it
If it turns out to need real work, this is what usually does it — with pricing published up front, so there are no surprises.
Prefer we reach out?
We respond within the hour during business hours — usually faster.
This guide describes common patterns, not a diagnosis of your specific vehicle — that takes an inspection. If your symptom is marked urgent, treat it as urgent. When in doubt, stop driving and call (779) 888-5000.
Stop wondering. Start knowing.
A proper diagnosis costs less than a wrong guess — and ours is applied to the repair.
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