A quality ethylene glycol coolant, containing corrosion inhibitors should be used. A 50/50 mixture of water and coolant is recommended. Antifreeze concentration should be high enough to maintain freezing protection down to −34°F (−37°C).
CAUTION
When draining the coolant, keep in mind that cats and other animals are attracted
by ethylene glycol antifreeze, and are likely to drink any that is left on the
ground or in an open container. This can prove to be fatal in sufficient quantity.
Always drain coolant into a suitable container. Coolant may be reused unless
it is contaminated or several years old.