You know it's a serious problem when it looks like your car is bleeding.

Dripping red fluid is the clearest indicator that the vehicle is leaking automatic transmission fluid. According to the Car Care Council, this fluid is involved in everything from cleaning and lubricating the transmission to transmitting force and pressure.

The transmission is an essential system in bringing power from the engine to the vehicle's wheels. A torque converter connects with the engine to adjust the flow of engine torque into the transmission, which transmits output power to the driveshaft and axle.

The transmission is subject to regular wear and tear, but certain driving habits can speed up the likelihood of a problem. These habits include towing heavy loads and driving in harsh conditions. The transmission can also be affected by the quality of the transmission fluid and the regularity of maintenance.

Transmission fluid leaks are more likely to appear after a vehicle has been driven 70,000 miles. Kenny's Transmission, an auto shop in Greenwood, Ind., says the leak can range from a few drops visible under the car to a more steady loss of liquid, the latter of which requires attention as soon as possible.

The transmission's position on the vehicle makes it more vulnerable to debris on the road. The automotive website CarsDirect says the rocks and other items kicked up by the tires may damage the fluid lines or transmission itself. In addition to harming the performance of the car, the site says transmission fluid leaks are bad for the environment since they can contaminate soil and water.

The AGCO Automotive Corporation of Baton Rouge, La., says transmissions will hold between eight and 14 quarts of fluid. Newer vehicles can compensate for leaks by giving priority to the hydraulic circuits, but this reduces the lubrication and can cause the transmission to burn out if the leak is not repaired.

Most transmission leaks that occur when the engine is running are a result of pressure issues. Visually inspecting components that are pressurized, such as the front pump seal and side covers, will let you know if they are leaking.

Cooler lines are a common source of pressure-related transmission fluid leaks. If the lines or their mountings have been warped, they will be more susceptible to leaks.

Fluid will collect in the transmission pan once a car has been shut down for significant period of time. This tendency might allow the level of fluid to reach a point in the pan where it will seep out, but other leaks may start above the pan before dripping down.

The collection of fluid in the pan makes it a common source of leaks, especially if it has a cracked or warped gasket. Improper resealing of the pan after transmission servicing can also cause leaking. Tightening the pan's bolts is often a recommended solution, but doing so can also damage the gasket and create a new leak.

Kenny's Transmission says that small leaks can be repaired by pouring "stop leak" fluid into the transmission fluid basin. However, AGCO Automotive Corporation advises against this solution, saying it acts by swelling the seals and may cause damage to the transmission.

Taking the vehicle to a mechanic to have the transmission serviced will usually result in an easy fix for the leak. In addition to installing a new gasket or seal, a mechanic can provide new fluid with conditioners designed to keep the seals tight and prevent further leaking.