Common Car Leaks, and How to Diagnose Them.

Eddie Carrara

Will I break down? Will I be left stranded? Will I make it to work on time? Are my kids safe? Is my car going to blow up? These are just a few of the thoughts that might be going through your mind when you see a fluid leaking from your car.

At one time, it was easy to figure out what is leaking from your car just from the color of the fluid, now it's almost impossible because the fluid colors have all changed. Coolant was only green at one stage of the game, now it comes in a variety of colors, from green, orange, pink, even purple.

So how do you know what fluid is leaking from your car? It all boils down to process of elimination, we will look at color, texture and smell, we will also look at the area from which the leak is coming from to help you decide what's causing the leak.

What Color is Coolant/Anti-freeze,
What does it Smell Like?

Engine coolant comes in a rainbow of colors because car manufactures have branded their own coolant to make a few extra bucks. Every manufacturer has its own coolant with their label on it, so it makes it a bit harder to go to the local auto part store and buy a gallon of generic coolant.

If your car leaks, and you need to add coolant to your engine/radiator, it's a good idea to stick with the same brand so the colors do get mixed and cause you to have brown coolant. Remember how you use to mix your water color paints when you were a kid? The same thing will happen in your radiator if you're not careful. Check you coolant color first before you buy, just look inside you overflow tank.

If you were to put coolant on your finger, you'll notice it has an oily feeling to it, but not like engine oil, more like soap or shampoo, and it rinses off easily, unlike motor oil. If you were to smell coolant, it smells sweet like candy and it even has a sweet flavor because it's wood alcohol (don't ask how I know what it tastes like).

If you suspect your car leak might be coolant, try to locate where it's coming from, the most common area for a coolant leak is the front of the vehicle, right under the radiator, but coolant could leak from anywhere, even inside your car. If you have to add coolant to your radiator, be sure to add a 50/50 mix of coolant and water.

Some coolant's come premixed to make it easy for the consumer. If you happen to buy straight coolant, I recommend owning a hydrometer to test the concentration level of the coolant, even if you live in an area that never gets cold, you need to have a mixture of water and coolant to protect your engine from corrosion and overheating, so have an Engine Coolant Hydrometer in your toolbox, their cheap and they don't go bad.

If you have a coolant leak in the radiator or heater core, I recommend using a Bar's liquid stop leak for a temporary fix, Bar's leak is one of the better stop leak products because it will not clog your radiator or heater core like other stop leak products. Using Bar's leak will buy you some time until you have the money to repair the leak properly.

What Color is Oil, What does it Smell Like?

Maybe your car leaks oil? First pull the engine oil dipstick and check to see what color your oil is. Oil is generally gold in color but it really depends on brand, some brands are very dark amber, like a lager beer. The texture is very slippery on your fingers and it will be difficult to wash off, you will definitely need soap to wash it off.

Motor oil has a smell like burnt butter or cooking spray, like when you turn the stove burner on high and the pan starts to smoke. Engine oil gets extremely hot and has that burnt smell to it with a hint of fuel, especially motor oil that is at the end of its life.

Motor oil tends to get very dark when it is in an engine for a long time because it collects unburned gases and debris from the engine; this causes the oil to become dark along with a few other factors. Motor oil has a very unpleasant taste as well, again, don't ask!

Some of the most common areas for oil leaks are the valve cover gaskets, timing covers, oil filters, and oil drain bolts. If you suspect your car leaks oil, place a piece of cardboard under your car and try to pinpoint the area where the leak occurs. Even if you don't plan to fix it yourself, you can let your mechanic know where the leak is coming from; it will save the mechanic time, and you money.

If your car leaks oil and you can't seem to locate the point of origin, try using Tracer Products TP34000601 UV Fluorescent Leak Detection Dye - Set of 6 , but you will also need this Uview 413010 Battery Powered, 6 LED Leak Detection Light . I use this die and light to find those tough leaks that have me scratching my head.

What Color is Automatic Transmission Fluid,
What does it Smell Like?

If your car leaks automatic transmission fluid, don't confuse it with power steering fluid. Automatic transmission fluid is red or pink unless it's very old and abused, then it tends to be brown or dark gray. If your transmission fluid is another color other than red or pink, I recommend changing it, it will improve the shift quality and the life of your transmission.

Automatic transmission fluid is very slippery to the touch and it smells a little like cooking oil, you will need soap and water to remove it from your hands. The most common transmission fluid leak is an axle seal or an output shaft seal. If you think your car leaks transmission fluid, again, place a piece of cardboard under your car to locate the leak.

For information on transmission fluid leaks, go to Car Leaks Red Fluid.

What Color is Brake Fluid,
What does it Smell Like?

If you think your car leaks brake fluid, Don't drive it, tow it! Brake fluid is clear, sometimes with a tint of amber, but very faint. Brake fluid has a dry oily feeling like dry tanning spray, and it's is very corrosive to paint.

If you ever spill brake fluid on your cars paint or even if you transfer it from your hands to the paint, remove it as fast as you can with window cleaner or windshield washer fluid, it will neutralize the corrosive properties in the brake fluid and will stop it from destroying your paint.

Brake fluid has a funny smell; it smells a little like fish oil or castor oil. If the brake fluid has never been changed, the brake fluid in the reservoir will turn green because brake fluid attracts moisture, so the moisture trapped in the brake fluid reservoir will have algae sediment in it.

This can be cleaned very easily, just break out a turkey baster, and suck the old fluid out of the reservoir, and then replace it with new fluid. If you're a mechanic or you work on cars often, I highly recommend buying this Mityvac MV6835 Vacuum Brake Bleeding Kit , I am the only one in the shop who owns this mini vacuum kit and everyone want's to borrow it, it works on all fluids and I use it multiple times a day.

The most common brake fluid leaks are flex lines, and master cylinders. If your master cylinder is leaking, it will usually leak into the car near the brake pedal. If a brake flex line, caliper, or wheel cylinder is leaking, it will leak at, or near a wheel.

What Color is Power Steering Fluid,
What does it Smell Like?

What if your car leaks power steering fluid, how would you know? Some manufactures use transmission fluid as power steering fluid, but you can buy fluid specially made for power steering systems, it's called, you guessed it, Power steering fluid!

Power steering fluid has a unique smell; it reminds me of how a marshmallow smells when it catches on fire, so it has a burnt smell, and no, I don't know what it tastes like, but I'm sure it doesn't taste like a burnt marshmallow.

The most common leak in a power steering system is usually at each end of the steering rack, at the rack end seals, if you have rack and pinion steering. If your vehicle has a steering gear box, generally the fluid leak would be at the seal at the bottom of the steering gear box, but most vehicles on the road today have rack and pinion steering.

If you suspect the power steering has a leak, look at the steering rack boots, notice if they're wet with power steering fluid. If they are, you may need to replace the complete steering rack.

For information on power steering fluid leaks, go to Car Power Steering leaks

In the above picture is a leaking power steering rack that is out of the vehicle. Typically you'll see the rubber boot start to discolor because of the power steering fluid trapped behind it, eventually it will seep through the rubber boot and start dripping on the ground.

What Color is Differential Fluid,
What does it Smell Like?

Is your car leaking Differential fluid? Differential fluid is a very thick and stinky lubricant, if you get it on your hands or your skin, you will smell it for days. Differential fluid is the color of honey and it's just as thick, old differential fluid tends to turn gray because of the metal dust mixed with it from the gears meshing. I don't have a description for the smell, all I can say is it is very pungent.

The most common leaks of differential fluid would be the axle seals and the pinion seal. If you think you may have an axle seal leaking, it's a good bet that you will see fluid leaking at the hub area near the wheel bearing, and if the pinion seal is leaking, it will be leaking near the u-joint closest to the deferential.


Well, I covered all the possible car leaks here by describing what their color could be and what they smell like.

If you have any questions, please ask, there are no stupid questions when it comes to vehicles, plus, someone else might have the same question and is too scared to ask, so just ask.

Comments (3)
No. 1-3

Thanks for your article. It is written so well, you are so talented. Unfortunately, I was never able to write a good essay, That’s why I ordered it on different sources basically and I get on well


This is really useful! Great article, thanks. It would be so cool if such things were told in colleges and universities. Say, instead of writing tasks like essays and so on. Students anyway nowadays try to avoid doing it all on their own. They spend time on such sites where you can find reviews on writing services and then they choose any.

Simply Lovable
Simply Lovable

Hello Scotty, I drive a 2004 model Honda Accord with 4 cylinders. I observed oil leakage from the engine area, can I use AT-205 to stop this leakage. What quantity should I use?

  1. I went for Jack wash of my car and it started making squeaky noise after. I saw a video you made spraying AT 205 on the bushing, can I do the same and do I need to mix AT-205 with water before use?

  2. Can I use Engine restorer and AT-205 Reseal together?

  3. When I turn my steering almost totally to any end, it gives a clicky noise, was told by a mechanic to change the power steering pump. Is this true or is there any other thing that could be done. Thank you.