We are really sorry, but we don't have cooling fluid capacity for 2003 BMW 6 Series Sedan Second generation yet :(
If you have any technical data, service manuals, owner's manuals, etc. for 2003 BMW 6 Series Sedan Second generation don't hesitate to share it with our community. You will help a lot of people sharing knowledge you have.
DIY car service is not as difficult as it looks like and it might save you thousands of dollars per year. It might be even fun and a good thing to do with your kids on a weekend to teach them how basic machinery works. It's really hard to screw something up and damage your car permanently if you use right tools, follow BMW 6 Series Sedan service manual and use right parts and fluids in prescribed amounts. Even modern cars stuffed with electronics can be serviced in your garage or even in your driveway. Changing engine oil, brake fluid, ATF, replacing brake pads, and etc. It's all may be done by yourself in a mater of a couple of hours.
Doing basic service for your 2003 BMW 6 Series Sedan you're not only saving money, but also also improving your technical skills and learning something new.