Late March is when the snowbanks finally shrink and the driveway reappears, and with it the calls that start the same way: “There's a spot under my car. Should I be worried?” Some of the time the answer is no — meltwater, salt crust and old stains that spent the winter hidden under snow. But a winter of salt and freeze-thaw is also hard on the seals, hoses and lines that hold your car's fluids in, and spring is when a lot of them start to weep. Knowing what fluid is leaking from my car is the difference between “mention it at the next oil change” and “don't drive it.”
The good news is that most leaks give themselves away. Every fluid under the hood has its own color, smell and feel, and each one tends to drip from a predictable part of the car. At Vorenza Auto Repair in Derry we trace leaks back to the source on a lift every week, and this guide walks you through the same clues we start with, so you can work out what you're looking at before you call.
Clear water, no smell, behind the front wheels: almost always air-conditioning condensation. Normal.
Light brown to black and slick: engine oil. Check the dipstick and book a look.
Green, orange, pink or yellow and sweet-smelling: coolant. Get it found soon, and clean it up — it's poisonous to pets.
Clear to amber, slippery, near a wheel — or a soft brake pedal: brake fluid. Don't drive.
Smells like gasoline: don't start the car. Call for help.
First, get a clean sample: the overnight cardboard test
A driveway is a terrible place to read a leak. Old stains, rainwater and the color of the pavement all get in the way, and you can't tell whether a spot is from last night or from sometime under last month's snow. In mud season it's worse: wet pavement, sand and melting salt hide everything. A piece of cardboard fixes that.
- Park on a level spot after a normal drive, so the fluids are warm and circulating.
- Slide a large piece of white cardboard (or a flattened box with paper taped over it) under the engine and the middle of the car.
- Mark where the front wheels are on the cardboard, so in the morning you know exactly which part of the car the drip came from.
- Check it the next morning. White shows the true color. Note the size of each spot, touch it with a paper towel to feel the texture, and give it a sniff.
Take a photo of the cardboard with your phone. It's the single most useful thing you can bring to a shop, because it shows color, location and amount at a glance.
What fluid is leaking from my car? Start with the color
Color gets you most of the way there. Smell, texture and where the spot is will confirm it. These are the usual suspects:
| What you see | Usually | Where it shows up | How urgent |
|---|---|---|---|
| Clear like water, no smell, not slippery | Air-conditioning condensation | Just behind the front wheels, usually toward the passenger side | Normal. No action needed. |
| Light brown when fresh, dark brown to black when old; slick and oily | Engine oil | Under the front of the car, below the engine | Soon. Check the dipstick and book a look. |
| Red or pink, turning brownish as it ages; thin and oily | Automatic transmission fluid, or power-steering fluid on some cars | Middle of the car (transmission) or the front (power steering, cooler lines) | Soon. Running low can damage the transmission. |
| Bright green, orange, pink or yellow; watery; sweet smell | Coolant (antifreeze) | Front of the car, under the radiator or near the engine | Soon to urgent. Watch the temperature gauge. |
| Usually blue, sometimes green, orange or pink; thin as water; smells like window cleaner | Windshield washer fluid | Near a front corner, under the washer reservoir | Low, but don’t put it off while the roads are still salty. |
| Clear to yellow when fresh, amber to brown when old; slippery | Brake fluid | Inside a wheel or tire, along a brake line, or at the back of the engine bay | Urgent. Don't drive. |
| Thick, dark and gear-oily, with a strong sulfur smell | Gear oil (differential, manual transmission or transfer case) | Middle or rear of the car, under an axle | Soon. |
| Very thin, evaporates fast, rainbow sheen, smells of gasoline | Fuel | Under the fuel tank at the rear, along the lines under the car, or near the engine | Urgent. Don't start the car. |
Treat the colors as a starting point, not a rule. Coolant comes in several colors depending on the brand and the type your vehicle calls for, washer fluid is dyed whatever the maker chose, and every fluid darkens as it ages. Your owner's manual lists exactly which fluids your car uses. A smell or a feel that doesn't match the color is a clue in its own right.
Once you start running the air conditioning in warm weather, expect this one. On a humid day the A/C pulls moisture out of the cabin air and drains it out under the car through a small tube, usually just behind the front wheels toward the passenger side. After a long drive with the A/C on, it can leave a surprisingly big puddle. That's normal. So is a little clear water dripping from the tailpipe on a cool morning, which is condensation from the exhaust. If the “water” is slippery, colored or smells sweet, it isn't water.
Where the spot is tells you as much as the color
Line your cardboard up with the marks you made for the front wheels and you can usually tell which part of the car is dripping. Here's what each area usually means.
→Under the front, below the engine
The busiest spot. Brown or black means engine oil, often from a gasket on top of the engine that has dribbled down, the oil pan, or a drain plug that wasn't sealed properly. Green, orange or pink farther forward points to the radiator, its hoses or the water pump. Check first: the dipstick and the coolant reservoir.
→Just behind a front wheel, toward the passenger side
If it's clear and odorless, this is where A/C condensation drains, and it's nothing to fix. If it's colored or slick, the same area also has hoses running to the heater core and, on many cars, the transmission cooler lines.
→The middle of the car
Red or pink fluid here is usually the transmission: the pan gasket, a seal, or the lines that carry fluid forward to be cooled. Brown here on a rear-wheel or all-wheel-drive vehicle can be oil from the back of the engine or gear oil from the transmission or transfer case. Why it matters: transmissions don't tolerate running low, and they're among the most expensive parts on the car to replace.
→The rear of the car
Thick, smelly gear oil under the rear axle points to the differential. A gasoline smell back here usually means the fuel tank, its filler neck or the lines running to it. Clear water dripping from the tailpipe is exhaust condensation and nothing to worry about.
→At a wheel, or on the inside of a tire
Wetness on the inside face of a wheel or tire, especially if it feels slippery, is a brake fluid warning until proven otherwise. It can come from a caliper, a wheel cylinder, a rubber brake hose or a steel brake line. If it's ignored: a brake system that's losing fluid can lose braking power with little warning.
Most reservoirs are translucent with MIN and MAX marks, so you can check a level without opening anything. This car uses pink coolant; yours may use green, orange or yellow.
Check the level that matches the leak
Once you have a suspect, the matching fluid level tells you how fast it's going. Do this with the car parked on level ground and the engine off and cool.
- Engine oil: pull the dipstick, wipe it, push it all the way back in and pull it again. The oil should sit between the two marks. If it's at or below the low mark, add the oil your owner's manual calls for before driving. Dark, gritty oil on the stick means it's due for a change as well as a top-up.
- Coolant: read the plastic overflow reservoir against its MIN and MAX marks. Never open the radiator cap or a pressurized reservoir cap on a hot engine, because the coolant can spray out scalding.
- Brake fluid: the small reservoir on the driver's side, near the back of the engine bay, has its own MIN and MAX marks. A slow drop over many months is normal as pads wear. A sudden drop, or any fluid around a wheel, is a leak.
- Transmission fluid: some cars still have a transmission dipstick, checked with the engine running per the owner's manual. Many newer cars don't, and the level has to be checked on a lift.
- Washer fluid: fill it. If it's empty again within days and you haven't been using it, the reservoir or a hose is leaking.
If a level is dropping, you've confirmed the leak. If the level hasn't moved and the spot is small, you have time to plan the repair rather than rush it.
How fast is too fast? Drips, spots and puddles
Almost every car seeps a little as it ages. What matters is how much, and what the fluid is. This is roughly how we'd judge it.
| What you find | What it means | What to do |
|---|---|---|
| A few drops, or a coin-sized spot after a night parked | A slow seep | Check the level weekly and mention it at your next oil change. |
| A palm- to plate-sized spot overnight | A real leak | Check the level before each drive and book a look in the next week or two. |
| A puddle, or a steady drip with the engine running | A fast leak | Get it looked at now. Don't drive far, and don't drive at all if it's brake fluid or fuel. |
| Any leak plus a warning light: oil pressure, temperature or brake | The leak is already affecting the car | Pull over and shut the engine off. Call for help rather than driving on. |
Two exceptions to “small means it can wait.” Brake fluid and fuel are never small. Any brake fluid leak or gasoline smell means the car stays parked until someone looks at it.
Why it's worth fixing a leak before it gets worse
Leaks rarely stay the same size. Gaskets and seals that have started to weep usually keep going, and a slow drip has a way of turning into a fast one on a long drive. What's at stake depends on the fluid.
- Oil dripping onto a hot exhaust makes a burning smell and smoke from under the hood, and it's a fire risk. It also softens the rubber hoses and mounts it soaks into. Run low enough and the engine itself is at risk.
- Coolant going down means the engine can overheat once the weather warms up and you're sitting in traffic. If your temperature gauge starts creeping toward hot, pull over and shut the engine off before it reaches the red, and have the cooling system checked.
- Transmission fluid loss shows up as slipping, harsh shifts or delayed engagement — the signs in our guide to transmission slipping — and transmission repairs are expensive. A seal or a cooler line is a far smaller bill.
- Brake fluid loss leads to a pedal that feels soft or sinks toward the floor, and it's a reason to park the car. Brake noises are a separate set of warnings, covered in our guide to brakes squeaking or grinding.
There's also the driveway, the garage floor and everything downhill of them. Oil and coolant that wash off pavement end up in storm drains. Catching a leak early keeps the mess, and the bill, small.
From underneath, a leak usually leaves a wet trail that leads straight back to the gasket, hose, seal or line it's coming from. That's the part that needs fixing, not the drip.
What finding and fixing a leak costs at our Derry shop
Finding a leak is usually quick. Fixing one ranges from tightening a clamp to replacing a seal deep inside the car, so we quote the repair once we know exactly what's leaking.
| Service | Price |
|---|---|
| Oil change with multi-point courtesy inspection Covers up to 5 quarts; additional oil is $8.95 per quart. Includes a fluid level check and top-off, and the inspection flags fluids that are out of spec. | starting at $89.95 |
| Brake inspection If you suspect brake fluid: pads and rotors measured, with the fluid, hoses and brake lines checked. We confirm any charge before we start. | typically free |
| Warning light code read If a light came on with the leak. Quick code reads are typically free; full diagnostics involve technician time, so a fee may apply, and we tell you before we start. | typically free to read |
| Leak repair — gaskets, seals, hoses or lines Quoted to your vehicle once the source is found, with parts and labor broken out on a written estimate. | custom quote |
Nothing gets fixed until you approve the estimate, and every repair we perform is backed by a 12-month / 12,000-mile warranty on parts and labor. A fluid check is part of every oil change and maintenance visit; leak repairs are part of our repair services, and if a warning light came on with the leak, it goes through our diagnostics process. While the car is in after a winter of salt, it’s worth having the hoses and belts looked at too.
Coolant tastes sweet to animals, and as little as a teaspoon can be deadly to a cat. Many brands now add a bittering agent, but older jugs and spills can still be dangerous. Soak up any puddle with cat litter or paper towels, bag it, and hose the spot down. If you think a pet has licked some, call a vet immediately rather than waiting for symptoms.
Fluid leak FAQs — from drivers in Derry, Manchester & Southern NH
What do the different colors of car fluid leaks mean?
As a rule of thumb: clear water with no smell is usually air-conditioning condensation; light brown to black and slick is engine oil; red or pink is usually automatic transmission fluid or power-steering fluid; bright green, orange, pink or yellow with a sweet smell is coolant; thin blue liquid is usually washer fluid; clear-to-amber and slippery near a wheel is brake fluid; and anything that smells of gasoline is fuel. Colors vary by brand, so smell, texture and location help confirm it.
Is it normal for water to drip from under my car?
Usually, yes. On a warm, humid day the air conditioning pulls moisture out of the cabin air and drains it under the car, typically just behind the front wheels toward the passenger side. A few drops of clear water from the tailpipe on a cool morning are normal too. If the liquid is slick, colored or smells of anything, it isn't water.
Is it safe to drive with an oil leak?
A slow seep that leaves a small spot overnight is usually safe to drive on for now, as long as you check the dipstick regularly and keep the level topped up. Stop driving if the oil pressure light comes on, if you smell burning oil or see smoke from under the hood, or if the leak leaves a puddle rather than a few drops. Book it in either way, because leaks rarely fix themselves.
What does it mean if my car is leaking green or orange fluid?
Bright green, orange, pink or yellow fluid with a sweet smell is almost always coolant, also called antifreeze. Keep an eye on the temperature gauge and the coolant reservoir, and get the leak found soon, because running low can overheat the engine. Clean up any spill right away: coolant tastes sweet to animals, and as little as a teaspoon can be deadly to a cat.
What does a brake fluid leak look like?
Brake fluid is clear to yellowish when fresh and turns amber to brown with age. It feels slippery, a little like light oil, and it usually shows up on the inside of a wheel or tire, along a brake line, or under the brake reservoir at the back of the engine bay. A brake fluid leak can lead to a soft pedal or a loss of braking, so don't drive the car. Call to have it looked at or towed in.
How much does it cost to find and fix a fluid leak at Vorenza?
Every oil change at our Derry shop, starting at $89.95, includes a multi-point courtesy inspection that flags fluids that are out of spec, which is often where leaks get spotted. Brake inspections are typically free. The repair itself depends on what is leaking and where, so we trace it to the source and give you a written estimate before any work. We work by appointment only, open daily 8am–6pm, at (603) 825-3815.
Bottom line: read the spot, then act on it
When you're wondering what fluid is leaking from my car, a piece of cardboard and two minutes with the color chart will usually get you to the answer. Clear water in warm weather is usually the A/C. Oil and coolant leaks need finding before they grow. Brake fluid and fuel mean the car stays parked. And if you can't place it, a photo of that cardboard gives us a head start on finding it.
Questions first? Call (603) 825-3815 or send a message through our contact form. Buying a used car with spots under it? Have it inspected before you sign — a leak found then is a negotiating point instead of a surprise. We serve Derry, Manchester, Londonderry, Salem, Windham and the rest of southern New Hampshire.