Get familiar with the oil dipsticks on sump and gearbox. Before each run, check the oil level in sump and gearbox. It really is a fundamental.
Temperature rise is not a reliable indicator of an engine with low oil. All that happens is that the thermostat winds open to cool the frying motor. When that is overwhelmed, the water temperature will rise. By then, you are already scored and rattling. Lack of oil will score vital components but it tends to be localised at first. Very little oil leads to overheating and rattling. No motor will survive it for long.
It sounds like you have not rattled it yet. Pour some oil in there and keep checking it. Stick a mirror under the motor to trace the leak.
Treat the lubrication oils as the life-blood of that motor. If the lubes are maintained, the motor will last for decades.