Concentrate or ready mixed coolant?

[LukeZS96]

so the IMG in the Zed has decided to give up the ghost so I'm going to change it over the weekend along with new coolant which is due a change anyway and I was just wondering whether to get concentrate OAT coolant or just ready mixed OAT coolant. If I need concentrate what is the best ratio for the K-series?

[talkingcars]

You need to use distilled water, tap water has silicates in it which are not good.

IIRC it should be 50/50.

Once you've bought distilled water it isn't much cheaper to buy concentrate.