[Rufton]

50/50 ethylene glycol w/ a 15 psi cap boils at approx 265F. Engine may self destruct quickly after significant percentage of coolant exceeds boiling point. Engine may self destruct at lower indicated temp. Temp sender may not accurately measure coolant temp, so max "oh crap" temp indication can vary. I like to make a note of normal operating temp indication so I'll know when things are getting heated. Oil temp and head temp are useful data points if overheating is suspected.