i asked this very question nearly 15 years ago whilst at college learning motor vehicle engineering... aparently antifreeze doesnt have the same cooling properties as water..... if that has changed since then i have no idea....

Ahhh... That'll be why it's running hot then! :rolleyes:

Just tried again after running the engine and the test tool is reading exactly what I would expect, around 40-50%. :speechless-smiley-4 I guess the antifreeze settles out on top of the water if it's left for a few days.

One more point to make about 100% antifreeze mix... pure antifreeze will freeze at only -7 oC !

did a little search & found this... not quite -7 but getting that way