As I related in my thread here:
Reporting From the Mother Road!
I just completed a 4,200+ mile trip which included temps in the tipple digits and desert and mountain driving...while I wasn't driving near the vehicle's performance edge or flogging it in any way, I certainly do drive "spiritedly" (which is one of the reasons I have a Z in the first place)...I'm happy to say that even under the most demanding conditions, the Z never faltered and the engine oil temps only once went near the 250 range (and only then after an extended trip up a mountain range which involved an elevation change of several thousand feet) - in all other occasions throughout the trip the temps hung around the 200-220 range.
I'm not saying this "proves" anything but I can say that any concerns I had about the "engine oil temp" issue have been pretty well answered for me unless I want to track my car (which I don't plan to do).