If you have a clear parking space, you can use the ground beneath the car to gauge your car's conditions. Whenever you find a puddle of fluids under the car, you can use its characteristics to identify it and get a clue on what is ailing your car. Here are four examples of such puddles, and what they may mean for your vehicle:
Dark Brown or Black
Used oil is dark brown or black; so if this is the color of the puddle under your car, then you know it is leaking oil. You can confirm your suspicions by dipping a finger (gloved) into the puddle and smelling it; in addition to the characteristic oil odor, used oil also has a slightly burnt smell. Another thing to use in your diagnosis is the location of the puddle; oil leaks are usually found directly under the engine (front half of the car). Oil leaks typically point to damage to the filters, seals, valve covers or any other part that covers the fluid.
Puddles of clear water, especially those that occur just inside the rear edge of the front wheels, should not alarm you. In most cases, it is something as harmless as normal condensation from the car's air conditioner. This is especially likely if you parked the car after a driving for a long time and using the AC for a long time.
Coloured Watery Fluid
If the water is coloured, however, then you probably have a leaking coolant. Confirm your suspicions by checking if the color of the puddle is the same as your coolants color, which may be green, blue, bright orange, or even pink. Coolant puddle will form near the front end of the engine where the radiator is located. The culprit is usually a damaged coolant pipe, cracked radiator or worn water pump gasket.
Yellowish Fluid with Medium Thickness
A clear or yellowish fluid, which is thicker than water, but not as thick as oil, is probably brake fluid. Other possible colors for brake fluid include blue and crimson red. Brake fluid also has an oily feel to the touch.
Brake fluid leakage is dangerous because you need the fluid to stop your car; it provides the hydraulic pressure that transfers power from the brake pedal to the brake system on the wheels. The locations of such puddles are usually near the wheels or where the brake pedals are located. Therefore, call a mobile mechanic or have your vehicle towed to a repair shop (such as Wolverine Automotive); don't drive the car until it's fixed.
These are just four examples, but they show you can learn a lot from fluids that leak from your car. Whenever you find a significant puddle under the car, try to have it diagnosed to determine the type and extent of the damage. It may be something as harmless as condensed water, or as serious as leaking brake fluid.