Heres what I just read:
"For several hours after someone swallows it, everything seems fine. But the body is busy breaking down the antifreeze (ethylene glycol) into a number of substances that affect your blood chemistry, nervous system, and kidneys. After a few hours, someone poisoned by antifreeze may seem drunk or groggy and complain of stomach distress. After a few more hours, the victim may go into a coma. The kidneys can be damaged and stop making urine. If the victim survives, there may be permanent damage to the kidneys and brain"
A very risky and unpleasant way to ctb. And if you survive, you'll probably be permantley fucked.