Coolant???

[Synchro909]

So what did they suggest to use? How about guarding against rust and corrosion by using straight water?

Soluble oil. there are several brands on the market but the number has recently decreased as one particular company is trying to buy out the others to establish a monopoly.
Check out Gunk or Motor Medic or Penrite or......

 

[mcgarrett]

I use these products all the time with plain water during hot summer months in Texas. They inhibit corrosion and allow better heat transfer of the coolant when used as recommended. I drain and replace with 50/50 antifreeze during the winter months. Have not witnessed any corrosion problems; when I drain the coolant at the end of summer, the water still looks nice and clear and without any "orange" discoloration which would indicate to me the presence of rust beginning to form.

https://www.redlineoil.com/waterwetter

https://www.royalpurple.com/product/purple-ice-cooling-system-optimizer/