Automotive fluid leaks are signs of a problem that shouldn’t be ignored. If levels fall too low they can’t serve their function, leading to big and often expensive problems. There are lots more possibilities than engine oil or coolant. Brake fluid, power steering, and automatic transmission fluid are among the most serious. So if you notice stains or puddles on your garage floor or driveway then it’s well worth your time to figure out just what is leaking.
The size of a leak is also important. Do you see a few drops? A stain? A puddle?
Place paper towels, or flattened cardboard boxes over the spots. Then, after driving a while, park your car in the usual spot. This will make it easier to determine the color, location, and extent of a problem. You can also look under your car for anything that might be dripping.
Note: You can tell gasoline leaks by the smell, and even a small leak is a big fire hazard. Any problem with brake fluid leaks should also be taken extremely seriously.
- Light brown to black is probably engine oil. When new it’s light brown and nearly clear. When old it gets darker and more opaque. If it’s approaching black it’s past time for an oil change. With a little rain you may notice a shimmering oil slick.
- Red to reddish brown is likely transmission or power steering fluid. The color comes from a dye added to help in identification as different from motor oil. It can be difficult to tell the difference between power steering and transmission fluid.
- Transmission fluid is thinner than oil, but oily feel. Old fluid can be a darker reddish-brown or orange-ish and can have a burnt odor or smell like petroleum.
- Power steering fluid is a bit thinner still, and also a bit oily. Strangely, it can smell a bit like burnt marshmallows.
- Nearly clear to light brown is probably brake fluid. It also darkens as it gets older, starting from a transparent pale yellow to become dark brown when it needs replacing. Despite being a critical part of your vehicle’s braking system it feels slippery.
- A thin blue liquid is probably windshield wiper fluid. It’s watery and smells a little like window cleaner (no surprise there). But it can also be green, orange, or purple.
- Fluorescent green means a coolant (antifreeze) leak. Bright color dyes make this one easy to identify. All products used to be green, but now have many different colors —lime green, bluish-green, orange, yellow, and pink. You can check your radiator’s overflow reservoir to see what color yours happens to be. Coolant also has a characteristic sweet smell and feels a bit slimy.
- Orange might indicate old transmission fluid or windshield cleaner. Or coolant with a radiator little rust.
- Bright yellow is likely coolant.
- Pink is probably coolant, but might be power steering or transmission fluid.
- Clear is almost always just water condensed by the air-conditioning.
What to Do When You Spot Leaks
While you’re checking out those driveway spots, check the various reservoirs under the hood. Your owners manual will show you where they are. Top off any that are low, including motor oil, then keep a close eye on the levels. If they drop noticeably again then a prompt repair is in order. Another rule of thumb is that if there’s a puddle or any stain more than 3 inches across then immediate attention is needed.
Tip 1: If there’s a coolant leak check the hoses and water pump.
Tip 2: If you have to top off brake fluid, it’s time to visit your mechanic. If the level visibly drops over a few days you should no longer drive the vehicle — have it towed.