Quote:

I posted that to show that the benefit of the higher MPG is small, but if people want to go after it, that is their choice, and many people like a challenge.

I would guess that rubbery parts
.... hoses, seals, vacuum lines
would have their service life shortened
by increased temperatures.

I would guess that aluminum to cast iron junctions,
like cylinder heads, manifolds
would be most likely to warp at higher tempertures.

I would not think that cast iron against cast iron parts would be affected much.

Since bore wall wear goes down with increased coolant temperature
(Continental Motors research)
I would guess that maybe piston ring wear would go down too.

Much of this bore, ring and piston wear
is from acids that are best kept as vapor,
never as a liquid (electrolyte allows corrosion)
so higher temperatures that are above the mixture's boiling temperature reduce corrosion.
Similar to 50/50 anti-freeze and sea water,
these mixtures of acids in water boil at temperatures above 212 F.

Continental Motors now mainly makes aircraft gasoline engines, and I for one was sad to see the press release last month where they were sold to a Chinese company.



Not really sure how acids in the coolant effects the bore and rings. If you have coolant and coolant vapor in those locations your problems are a lot bigger. Generally, you're not "boiling off" anything as the system is normally maintained below boiling conditions. Finally, mineral acids have a higher boiling temperature than water, so if you boil an acid solution, the acid concentration in the remaining liquid likely remains the same or goes up. It would be type of acid specific.

Remember that coolant temp is only part of the story. It is a reflection of the efficiency of heat transfered from the engine to the coolant to the air for a given coolant and system. 220 or 230 degrees may or may not be okay. If everything else in the system is functioning properly and you have a high temp t-stat in the system, its probably okay.

Finally, the lower t-stat will allow a good system to operate at a lower coolant temperture, and the associated analysis is that the cylinder wall wear will increases. This is true, however,I can tell you in practice that it is small and likely unnoticeable in our good weather, limited usage cars. Note that nearly all marine automotive engines use a 142 degree t-stat and their opreating conditions are an order of magnitude more grueling than in a car.