carry antifreeze that is pre-mixed with high quality water. Invest in a good anti-freeze tester.    Don't be fooled by an ordinary hydrometer.  Use a refractometer for accurate results.  Always allow the cooling system to fully cool before performing any cooling system service.   http://www.eetcorp.com/antifreeze/antifreeze-faq.htm   http://www.imcool.com/articles/antifreeze-coolant/whygoodradsgobad.php      Auto Repair