On a related note, running a higher temp t-stat should not lower the vehicle's ability to handle higher ambient temps. A cooling system is designed with a capacity that matches the output of the engine up to a limit regardless of the which t-stat is installed. The temp of the t-stat simply maintains the operating temp of the engine within a certain "band".

If a vehicle overheats, it's not because the t-stat is too high, it's either because the output of the engine has been modified in excess of the radiator's capacity for the given ambient temp or the radiator flow is restricted by crud or a malfunctioning pump or t-stat. It can also result from a poorly designed cooling system where the radiator has no reserve capacity and the higher temp t-stat will run it so close to the limits that any unusual load or higher ambient temp will push it over the edge. This is the case on my beater Chevy. I swapped in a 350 into a V6 truck and kept the smaller radiator because I'm to cheap to swap it out for a bigger one. The only time it's a problem is when it's idling with the AC on in the direct sunlight in the summer. Still, it gets pretty hot but it never boils.

An 80C t-stat wide open will flow the same as an 85C. A common mod on Ford Diesel pickups is to run a 203F t-stat to pick up a little power and maybe a MPG.

In any event, like the others said, it's not a good idea to run without a t-stat...

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250