Engine Temp Normal-Max?

Folks, My Volvo diesel MD6A looks (to me ) to be running a little hot. Then it occurred to me that I might want to see what exactly "Hot" is. My owners manual does not say except that the thermostat is "fully open" at 165 or so. Does that mean that 165 is "normal" and above that woulde be high? If I run for a while at cruising RPMs of 2,300 I am at 185 degrees or so and I can run at that temp for hours it would seem. If I push the engine, it will go to 200ish but I don't do that because it seems high to me. How does that sound to you? Chris Cal31, Poulsbo, WA