> LIGHT BROWN OR BLACK STAINS - MEDIUM CONSISTENCY
> Ah, you're thinking, "That's easy ... engine oil!" You're right, we'll 
> start
> simple and stay simple -- we're all familiar with this the brown/blackish
> color of motor oil. Because of the oil system has many gaskets, lots of 
> heat
> (weakens seals and gaskets over time), and lots of pressure,  engine oil
> tends to be a frequent visitor. While a little oil seepage is not a 
> problem,
> any drips should be investigated. Pay particular attention to any lines,
> filters, or coolers external to the engine. Replacing an O-ring or 
> pressure
> line that is starting to leak is a wise move, as it offers peace of mind.
> Engine gaskets that leak need careful assessment -- they are not likely to
> fail completely and may be damn difficult to replace in-situ. Note: Did 
> you
> add new oil to the engine recently? Sometimes a simple mistake can lead to
> oil spills appearing later. Oil leaks that have continued for some time
> should lead to the buildup of dirt -- can you see any on your block or 
> sump?
>
> REDDISH, LIGHT BROWN OR BLACK - THINNER OR THICKER CONSISTENCY
> Stains, drips or puddles that look similar to engine oil, but are thicker 
> to
> touch and located near the center of the car, are usually from the
> transmission. While automatic transmissions used to use a reddish fluid
> thinner than engine oil, recent  units  employ a reddish fluid that is
> thicker. Note: overfilling the transmission with fluid seems to be a 
> common
> source of leaks -- check the temperature/ volume relationship.  Actual 
> leaks
> are most likely to come from the clutch side shaft seal or the output 
> shaft
> seal. Leaks are also possible from the pan gasket. Some engines (M70) have
> external coolers with connection lines and these can also leak.
>
> REDDISH OR LIGHT BROWN - THIN CONSISTENCY
> Sound like a familiar fluid? It should. If your car is equipped with power
> steering, then it has a fluid in the steering system that is either
> identical or similar to your car's automatic transmission fluid. Luckily 
> the
> power steering system is localized so any leaks should be easy to spot.
>
> CLEAR, SLIGHTLY BROWN AND SLICK - MEDIUM CONSISTENCY
> This is that critical fluid for your brake hydraulic system. When brake
> fluid is new, it is usually either clear (like mineral oil) or tinted
> slightly brown. But after time and with the accumulation of dust, rust
> particles and other contaminants, it can turn entirely brown. What you 
> need
> to remember is that brake fluid is characteristically slippery to the 
> touch
> -- more so than engine oil or automatic transmission fluid.
>
> DIFFERENTIAL FLUID - THICK CONSISTENCY
> Your car's differential uses a fluid that is similar to the standard
> transmission fluid. The key to distinguishing the fluid origin is where is
> drips. If it drips from the rear of your car, then the chances are that it
> is from the differential.
> Since this fluid is not pressurized, leaks indicate that something is
> significantly loose.
>
>
> YELLOW, GREEN PINK AND SLIMY - THIN CONSISTENCY
> Here it is: coolant. Slimy to the touch and one of the easiest fluids to
> identify, coolants come in a range of bright colors. Older cars simply
> dumped the coolant on the road or driveway when the engine got too hot. Of
> course, overheating maybe a sign of some other problem. Today's cars have
> closed systems that capture and recycle any blow-off. So, if you have a 
> late
> model car you shouldn't ever see coolant on your driveway or on your 
> carpet.
> If you do, it's a sign of potential trouble (e.g., leaky water pump or
> hoses).
>
> CLEAR, SHINY LIQUID - VERY THIN CONSISTENCY ... LIKE WATER?
> If you ever come back to your car in your driveway or in a shopping center
> parking lot and see a puddle of clear water under the front and on the
> passenger side, you don't need to panic. But, if you've been running your
> car's air conditioner, then the spot is most likely water that has 
> condensed
> on the air conditioning hardware and is harmless. The air conditioner has 
> a
> water drain tube to drip this innocuous condensed water out to the road --
> and there's no problem. If all fluids were only so innocent!