One of the most important fluids in your car is the Transmission Fluid. There is no way around getting your car to run properly without transmission fluid. This fluid is what makes your transmission turn and the gears shift. If you have a leak and there is little of no fluid in your transmission, then your car will not move. There are some signs you can look for if you think your car is low on fluid.If you have a large piece of cardboard, you can place it under the car. This will let you know if there is any fluid leaking form under the car. Leave the board under the car for at least a day in order to see if anything is leaking. Take the board out from under the car and look to see if there is any fluid on the board. If there is, you need to examine to see what kind of fluid it is. It if it red, then it is most likely transmission fluid.When you discover there is a transmission fluid leak, you will need to have it looked at by a mechanic immediately. Some leaks are not detectable until the mechanic looks underneath the car. You could also have an internal leak that is not showing up under the car. The fluid could be going to your oil reserve or to another part of the car. Sometimes when you have your transmission fluid changed, the bolt may not be tight enough and some fluid will leak around it. All you have to do is take it back to the mechanic and get them to tighten the bolt. If the fluid leak is large, you will either need to get the gasket changed or find out where the fluid is going. Do not run a car longer than necessary with no transmission fluid. This will damage the transmission more than if you would just get the fluid leak fixed.