50% Bluecol plus 50% de-ionised water in mine. At least, I think it was Bluecol ... I've slept since then! Always buy the neat stuff and mix it yourself. Any left over water can be used to top up batteries or used in SWMBO's steam iron, so added Brownie points to be gained!!
I read somewhere of BMW which had the wrong coolant put on by the dealer and the engine corroded and needed replacement I think you need coolant which is rated for aluminium bike engines to avoid internal corrosion.
There are three main types of coolant, IAT, OAT, and HOAT, You can use any of them, as they are all broad range and are designed to be compatible with a wide range of materials like cast iron, alloys, brass, rubber etc its just some shouldn't be mixed because of the additives they contain, However Triumph will probably say you should only use theirs because everything else is the devils spawn and will rot your engine...much like every car manufacture. https://www.aaa.com/autorepair/articles/engine-coolant-101-the-right-coolant-for-your-vehicle
I've put Evans waterless coolant in my Daytona, not cheep, as you have to flush first with prep fluid, but that is reusable. So far so good
I tried that, but the system ran hotter and the thicker liquid seemed to put extra strain on the water pump. Due to the higher running temp the fan was on all the time I promptly flushed it out and returned to normal Castrol blue
We ran waterless coolant on race 675 Daytona’s and it was faultless, it does run about 7 degrees hotter but never missed a beat
