Viper, I did some tests and it works!
If I keep the temperature below 120 the engine won't die. Unless the revs are too high, which makes the oil temp go boom. So I fight at 2850, and occasionally at 3000.
However, when I go high, above 4-5000m the oil temperature goes really high. The only was not to kill the engine is to reduce the revs to 2,300. Is that normal? Something is fishy up there, even the revs weren't constant. Perhaps the automatic mixture control is broken as some say?