There is a lot of info on this subject on the WWW. Here is just one link, but it is consistent with most of the others and is easier to read than some others. What it says is that there is double the engine wear at 160* as there is at 180* with no appreciable performance gain.
And if it matters, I always drill a couple of small bleed holes in my thermostats. Which, after some bad experiences with other brands is only the Stant Superstats.
