I wanted to replace the coolant in my 2005 Mustang GT - but I can't get all the old coolant out. A lot of research, and it's like no one else has this issue. The car takes something like 15 quarts but I can only get maybe 5 out at a time. American Muscle briefly states:

"The proper way to flush the system is to make multiple passes through the system with distilled water. Once the fluid becomes clear and appears to be completely water, the system can be replaced with the coolant of choice"

But how can I replace the water will coolant if I can only get 5 quarts out at a time, it is supposed to be 7.5 quarts of coolant. Strange how so many how-to guides don't seem to go into enough detail to properly cover this important detail.