Most home carpeting is made of synthetic fibers, and stains tend to set in fairly quickly with that kind of material. Motor oil is one stain that can be removed as long as you get to work on it as soon as it has been spilled on the carpet. A few supplies that you may already have around the house are needed to remove the oil, so get to work as soon as you see the spill happen.
Use a plastic spoon to scoop up any motor oil that is sitting on top of the carpet. Oil typically remains bonded together, so it is very likely that there will be a pool of oil sitting atop the carpet.
Use white paper towels to soak up as much oil as possible. Fold each towel sheet in half, and then in half again to make it thicker. Press the sheets against the oil to lift it from the carpet fibers. Do not rub the oil into the carpet, since that will cause it to spread and force the oil deeper into the fibers.
Soak a small section of a clean, white washcloth with rubbing alcohol. Dab the oil with the alcohol. The alcohol will break down the particles that help hold the oil together, making it easier to remove from the carpet. Continue adding more alcohol to clean parts of the cloth and repeat the process until no more oil is being lifted.
Pour several tablespoons of rubbing alcohol directly onto the oil spot.
Place a clean cloth over the alcohol, and lay weights or other heavier objects on top of it. This will keep constant pressure on the alcohol, pushing it into the oil to break it up. Keep the cloth and weights on the spot for a few hours.
Take the weights and cloth off of the spot, and allow it to air dry.
Vacuum the area when completely dry to lift the dried-up oil particles from the carpet fibers.