What do you put in your Yamaha yz80 radiator?

In Australia, the general competiton rules state that "water only" for road racing, as in GP80 style, I race a YZ80 / 85 in a GP chassis, so no slippery green stuff.

Yamaha suggest a corrosion inhibiter, and there are many radiator "ice" products on the market that are ment to improve the cooling benefits of water when used in the correct ratiOS or as a substitute. In the old days it was water soluble, machine cutting oil as a protector. And really if it's for trail riding or dirt racing who cares as long as it keeps the motor at the correct operating temperature and you can keep most of it in the radiator.