Coolant change + brake fluid change questions?

Hi Folks,

Coming up on my 4 year anniversery in July for my X-5 3.0 litre cooling changeover. Is there a difference between flush and drain? I checked my level and it's bare in the overflow expansion chamber (nothing to measure). I am going to Wallmart to buy some distilled water and the Dexron GM dyed stuff to top it off. Then I will proceed to test the antifreeze with a "Cool Trak" PH test strip to determine health of the antifreeze.

Next question: My local BMW dealer charges $75 an hour and said it would cost $100 for this changeover. It may include up to 2 gallons of antifreeze. Should I have them perform it versus the Joe at the garage to muck this process up to save $25-$40 for the job? And is it necessary to flush or just drain? The folks that have a nationally syndicated radio program I read stress the importance of testing your anti freeze twice a year and change it according to manual.


Finally, is it kind of anal to change your brake fluid over every two years? I had a VW scirocco and never touched the brake fluid in 11 years of ownership. Noticed my free maint. over and above the warranty that ran out last year at my BMW dealer ship never changed over the brake fluid at the first two year prescribed interval in the manual.

Thanks!

Ron