I think it might be time to swap the low temperature thermostat out of the loop...
and more worryingly;
even with a bit more stress on the engine it doesn't get a lot hotter on the water - but the oil comes up, but imo not far enough.
and more worryingly;
even with a bit more stress on the engine it doesn't get a lot hotter on the water - but the oil comes up, but imo not far enough.