Your car is not sitting in its usual place. You can tell this because of the telltale spot on the driveway or garage floor. Some type of fluid has dripped from your car. You have a leak. Before a leak can be fixed, it must be identified and located. The steps to take care of this are not difficult. A simple process can start you on the way to a solution.
Identify the type of fluid that is leaking.
Your vehicle has a number of different fluids that can develop a leak. Some are extremely critical to repair quickly while others are more of a nuisance than a big problem. The easiest way to identify what type of fluid that is leaking is to sample it. No, do not taste it. Use a paper towel and wipe a bit of it up. Check the color. A reddish color indicates that it is most likely transmission fluid. If it is mostly green, you are leaking coolant.
Next, check for power steering, brake, windshield washer fluids, or fuel.
Clear and oily is probably power steering or brake fluid. Since brake fluid has a distinctive smell, open your brake fluid reservoir and dab a little onto another piece of paper towel and compare scents. Depending on the brand, windshield washer fluid can be a multitude of colors, but usually will be either blue or orange. Gasoline and diesel fuel have such recognizable smells that you should not have a problem figuring these out.
Finally, motor oil is about the only fluid left to find.
Once you have eliminated these potential culprits, you are left with the reality that your car is leaking motor oil. Motor oil will be a little more viscous than the other fluids and will usually seem dark or dirty. Even immediately after an oil change, it will have a yellow or brown tint. It is a good idea at this point to degrease or power wash the engine and underside of the car to remove accumulated oil and grime so that the precise point of the leak can be better seen.
Once the leak has been identified as motor oil, you have to locate the source.
Use a large piece of paper, like newspaper, or cardboard to help you find the area where the leak is originating. As soon as you park your car for the night, slide the paper under the front end of the car. It needs to extend from just behind the front bumper about a third of the distant toward the back of your car. It also needs to cover the space to within six inches of the inside of both front tires. Obviously, if you drive a mid-engine or rear-engine vehicle, you may need to adjust where you put the paper. After the car has been sitting in the same place for several hours, a spot or spots should have appeared on the paper.
Do not move the car or the paper until you have looked for the leak.
Raise the hood to improve the light available around the motor. Lift the car on a jack until it is at a height that will allow you to slide underneath it comfortably. Follow safety precautions, such as, using jack stands and wheel blocks to reduce the chance of injury while under the car. If possible, have a second person standing by in case an emergency would arise. Use a creeper or some type of ground cover to lie on while sliding under the car to prevent ruining your clothing and reduce the chance of scrapes to your skin.
Crawl to the spot where the oil has stained the paper.
Looking up at the bottom of your car find the place where the oil is dripping from. If it is coming from your oil pan or drain plug, these are both easy fixes. The drain plug can be replaced with a slightly oversized plug to seal up most these types of leaks. To fix a leak around the oil pan, you will need to drain the oil, drop the pan, and replace the gasket. If your car is old, you may want to consider replacing the oil pump while you are at it if the pump is located inside the pan.
If the pan or plug is not the leak source, you have more investigating to do.
Track the path of the oil from the point of the drip up the side of the engine. Most likely, it will lead you to your valve covers on the top of the engine. Try to identify the area of the engine where the leak is most likely to be originating while you are under the car. Once you have traced it as far as possible from the bottom, slide out from under the car and look from the top. You should see oil seeping from edge of the pan on the side of the engine. This will tell you which pan gasket needs replacing. On most current model vehicles, it is best to leave this job to the professionals because there are so many other pieces to remove before you reach the valve covers.
If the oil is seeping from the side of the engine, you have a much bigger problem.
Usually an oil leak is not a way that head gasket problems are found. However, if you have a head gasket that is leaking in just the right place, you may have just saved yourself many hundreds of dollars by finding a bad head gasket before the head is damaged or coolant ends up in your crankcase. Definitely take this problem to a professional for repair work to be completed.