Non-emergency leaks. Motor oil is dark brown to black, with a rubbery smell and the texture of a thin, slick syrup. Powersteering fluid has a sweeter smell. Transmission fluid is thinner than either, reddish brown in color, and smells almost like burnt rubber. Antifreeze is more distinctive. It’s green, blue, red, or yellow, with a “plasticky” smell, and it’s just thicker than water. Don’t panic over a few drops of any of these fluids, but check and level off the corresponding fluid level regularly until you can have the leak’s source inspected by a pro.
Emergency leaks. “Fix ASAP” if the leak is brake fluid or gasoline. Brake fluid has a light bronze color, feels “slightly tacky,” and smells “like rancid nuts.” Gas is thin, clear or golden, and smells like, well, your last fill-up. A gas leak represents an “urgent” hazard—have your car towed right away.
Source: ShopSmart