300K on my motor before i opted to do a swap out for more power. also had a k5 with 330K when it sold... no stat in that truck either..... not to worried about a possibility of pre-mature wear. motors will last if you take care of their maintenance, fluid levels, and drive respectfully. i plan on putting 250K or more on the v-6 in my jeep.LOL, running no thermostat is a terrible idea, even in warmer climates. You’re keeping the oil from coming up to temperature for significantly longer, which speeds up the wear process and could lead to early failures.