[Pigeon Roost]

E-glycol and P-glycol based "coolants" may not be as efficient as plain water at transferring heat at normal operating temps, but BEWARE! Once water approaches its boiling point and steam emminates from the hot spots of the heads, effectively shielding those surfaces from the water, very rapid loss of ability to soak heat from the hot spots will allow over-heated areas to become larger and extremely hot in very short order.

The pressure of our systems does add a bit to the boiling point of water, but a GL1800 in parade mode would, in my opinion, easily overcome even that enhanced heat tolerance of water alone. The glycol coolants not only lower the freezing temp of the mix, they also extend the boiling point upward. Some coolants are available that eliminate the water alltogether, thus providing a very high heat tolerace (resistance to steam or boiling). The bike's temp will be a little higher if the system is stressed beyond the range provided by just water, but the harmful head warping temps are then very unlikely to be approached. Plus, up in that range beyond water's toleracnes, the higher contrast between the glycol based coolants and the outside ambient temperature will more than overcome any advantage in heat transfer efficiency that water had over the coolant at lower temps.

prs

 

[Pigeon Roost]

completed the anti-freeze change added the water wetter, had the bike ideling & see a difference in the temp already.
tomorrow I'm going to take it for a ride & will report back on the engine temps..

Are you sure of that observation? I think you really should NOT notice any difference at idle or normal riding conditons. Only at times when the cooling system is under stress should any such difference be observable and the OE temp gague would still not be very reliable then. Two things are working against you or for your (depending upon your point of view). One, the thermostat characteristic does not change when the chemistry of the coolant changes. It begins to open at about 165F or so and is fully open at about 190F or so. If the new coolant is more efficient, the thermostat is not going to be as far open and it will tend to keep the engine at a set temp regardless of coolant efficiency. The second thing is the temp gague programing. In is lower or cool range it probably responds with good sensitivity and linearly, but Honda has it set to hit its "sweet spot" at or just under midrange and then to be very insensitive to further upward temperature changes. That plateau effect is prety broad and more so on post '02 and even older bikes that had the "improvement campaign". Then, as the bike gets a lot hotter the temp gague increases very rapidly from about just above the mid point to buried at the upper peg. Thus, to make coolant efficiency changes you would have to average a bunch of stress runs and use a linear thermometer. At least that is the way I think it should work -- if I am misunderstanding the situation, please do correct me.

prs