Normal leaks vs. serious leaks: how to identify them and what they mean

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7 min read

If it hasn’t been raining and you spot a puddle under your car, chances are there’s a leak. You may be wondering what is wrong with your car or what part of the car is leaking. Or how severe the leak is, and what role smells and colors play into a leak’s diagnosis. Ahead, we separate fluid leaks into three categories to help you navigate fear and identify, diagnose, and fix various car-related fluid concerns. Let’s go!

types of auto fluid leaks

There are various fluids that can leak from your car over time. However, there’s a spectrum when it comes to the severity of the fluid, and how quickly the leak should be repaired in order to not create (further) damage to your car. Generally, if the puddle underneath your car is three inches or wider, regardless of color, texture, or odor, it needs immediate attention.

These are the most common fluid leaks based on location.

Front / under engine

Washer fluid (Cleans the windshield. Annoying, but not the end of the world. Look for a crack in the windshield wiper reservoir, or take your car for a check up.)

Power steering fluid (Provides steering navigation. Could become a safety hazard. Get checked out ASAP.)

Coolant (Regulates the engine temperature. You’re at risk of overheating. Head to a shop.)

Transmission fluid (Lubricates and operates the transmission. Contact a mechanic stat.)

Engine oil (Lubricates the engine. Do not drive your car.)

Near wheels

Brake fluid (Operates the brakes. Brakes can lose fluid quickly. Head to a shop.)

how to identify auto fluid leaks

This is where color, texture––and sometimes smell––come into play. These sensory details can provide a lot of information about the leak long before you hit up a mechanic. If car repair is on your mind, take a moment to identify the details of your leak before deciding it needs immediate attention. Generally, if the puddle underneath your car is between 1–2 inches wide and does not smell like gasoline, it’s referred to as a “drip” and is not considered a serious condition.

Red leak = power steering fluid or automatic transmission fluid.

Power steering fluid can range in hues of reddish-brown, depending on how old the car is. This fluid is thin and oily, and may smell like burnt marshmallows. A mechanic can take a look at this for you. Automatic transmission fluid starts out red, then turns a reddish-brown (and sometimes orange) the more it's driven. This fluid will smell like petroleum, and you’ll probably have noticed other signs of a transmission issue (like “slipping,” where your car doesn’t hold a gear, or it is continually searching for a gear). Best to have an inspection done. 

Orange leak = automatic transmission fluid.

Automatic transmission fluid can turn from red to reddish-brown, to orange as it ages, so it’s best to have a mechanic inspect the transmission to confirm.

Green, orange, yellow, or pink leak = coolant.

Coolant comes in many colors and can leak from many places throughout the cooling system––it’s bigger than you’d imagine. Leaking coolant is an indicator that there is rust in the car’s cooling system. This leak will smell sweet and have a slimy texture to it.

To note: The top cause of serious engine damage is loss of coolant, so if your car is constantly losing coolant, contact a shop immediately and have your cooling system inspected.

Blue leak = windshield washer fluid.

This fluid is thin and watery and smells like––you guessed it––window cleaner. This fluid comes in an array of similar colors (like green). If you’ve gotten a whiff of this scent, it’s best to check to see if your washer fluid reservoir is cracked, and then have a mechanic check its seals and lines.

Pale yellow leak = brake fluid. (Do NOT drive your car.)

This hydraulic fluid starts out as light yellow, then darkens over time into dark brown if not maintained. Brake fluid feels oily to the touch and is very slippery. It could also smell like fish oil. If you find this, it’s not safe to drive your car. Get your car checked out ASAP and have the brake system inspected.

Brown leak = engine oil.

This type of fluid starts out a lighter brown and darkens over time, becoming almost black after combining with dirt and other particles that circulate through the engine. Engine oil has a very distinctive smell and feels thick and slippery to the touch. If the leak is minor, you can keep your oil topped off––but still, have that minor leak inspected sooner than later.

Clear leak = water (A-OK!) or gasoline (Do NOT drive your car.)

If the fluid looks like water, feels like water, and is odorless, best chance it’s… water! This fluid is likely condensation draining from the air conditioner––no harm no foul. If you notice the distinct smell of gasoline paired with a clear leak, do NOT drive your car. Instead, call a mechanic for advice on next steps.

Washer fluid leaks

These come from extreme cold temperatures freezing the water––and windshield reservoir holding it––which causes a crack, and eventually, a leak. Tip: Drain and fill the windshield reservoir with fresh washer fluid (not water!) since the fluid contains alcohol and won’t freeze. There’s a couple different DIY methods to repair the reservoir, which includes using a fiberglass cloth, sandpaper, and epoxy. Coolant is an essential fluid––it prevents your engine from overheating in hot weather and freezing in extreme cold weather––so its levels should be routinely checked.

Finding a coolant leak is pretty simple: Allow the radiator to cool, take off the cap, and look for signs of oil in the radiator or header tank. If there's a minor leak, you may be able to use a sealant for less serious cracks and breaks.

Leaks can pose slight annoyances to serious problems on your daily commute and life. Leaks may also signal the end of the road for your car, which can be a bittersweet feeling when thinking about your next steps. If you’re ready to sell that leaky car, Peddle will pick it up free––regardless if the fluid underneath your car is from the engine or the environment.

how to fix auto fluid leaks

Before crunching numbers or getting a quote from your local repair shop, you may decide you want to take matters into your own hands. While some fluid repairs––transmission fluid, engine oil, and brake fluid––need the expertise of a mechanic or other trained professional, washer fluid and coolant leaks can be repaired if you have the skills, tools, and time.