Transmission fluid leaks and drips leave a reddish stain on concrete driveways. If you want to remove such a stain, do it as soon as possible after the stain gets there--petroleum-based fluids are removed much easier if dealt with right away. Though a concrete surface is hard, it is also porous and absorbs liquids deep down into the material. The complete removal of older stains is virtually impossible, but you can make the spot less obvious in about an hour. Using the right chemicals will make the surface portion of the stain fade or disappear altogether.
Fresh Transmission Fluid Stains
Smooth an even 1-inch layer of kitty litter over all fresh transmission fluid spots. Let it soak up the fluid for about 30 minutes, then sweep it up with a broom and discard.
Mix 2 cups of liquid dish detergent with 1 gallon of hot water. Pour the sudsy water over the fluid stains.
Scrub the spots with a stiff nylon-bristle brush. Rinse with clear water.
Repeat scrubbing with hot soapy water and rinsing until the stain is completely gone.
Older Transmission Fluid Stains
Pour a small amount of paint thinner over the old transmission fluid spots. Allow it soak for 15 to 20 minutes.
Scrub the area vigorously with a nylon-bristle sponge. Soak up the dark liquid using paper towels.
Mix two cups of liquid dish detergent with a gallon of water. Scrub the area using the nylon brush and rinse with clear water.
Place the paper towels in a disposable metal container or burn them in safe area.