I accidentily put antifreeze in to the "intensive action resevoir" in
my 1999 BMW 540i.  I want to know if I can still drive my car and what
the purpose of the intensive action resevoir is?  Also shoul i have
this drained? is it that big of a deal? Please help!

Hello dfolwell, I have never owned a BMW, but I do have experience
with antifreeze and automobiles in general. You ask about purpose of
the "intensive action rese(R)voir". I found this reference to get me
started:

http://bimmer.roadfly.com/bmw/forums/e39/6105995-1.html

I do not believe there is a separate reservoir for the rear window
washer.The only other washer reservoir is the optional
"Intensive-action washer reservoir" (CWP?). BMW recommends
"intensive-action washer fluid", which resists freezing to
approximately -17 degrees Fahrenheit for the intensive-action
reservoir. For the main washer reservoir, BMW recommends water and a
washer antifreeze if necessary.

So, it appears to me that the "Intensive-action washer reservoir" is a
fancy sounding name for a reservoir that holds a more agressive
cleaning solution formulated to remove bugs, road grime, etc. Here is
an interesting post from a BMW forum. I assume these owners know what
they are talking about:

http://www.totally-bmw.com/bmw/bmwnews/bmw/bmw-p-923.html

What is Intensive Action Washer Fluid 

Question: Is the BMW stuff any different from any regular washer fluid? Bug wash?

Answer: Most folks just fill it with neat (I assume he means straight)
screen wash....

Of course any "screen wash" whether sold by BMW or Walmart has to have
some type of antifreeze to keep it from freezing solid in the winter.
Therefore, I see no harm being done by having straight antifreeze in
the reservoir. It might be messy and not do a very good cleaning job,
but it certainly won't do any permanent damage. Also, straight
antifreeze will be thicker (more viscous) than the washer solution and
probably not spray very well from the nozzles.

I would try and siphon or use a cheap hand pump to get most of the
antifreeze out of the reservoir. Don't get any antifreeze in your
mouth and keep it away from any pets since it is not good for you or
them. You could probably use some 1/4 inch vinyl tubing and suck the
fluid out using a squeeze bottle of some kind. Once you get most or
some of the antifreeze out you could dilute what remains with your
normal washer fluid.

I hope that this helps you and relieves your fears that you have done
some real damage. If I can help you further, please ask for a
clarification.

Happy driving, Redhoss

thank you!!!!!!!!!!!!