Had three failures in cars and bikes , none in aircraft
1) Blocked oilway starved the camshaft of oil, no warning (oil pressure and temp read okay) but total loss of power when the camshaft seized.
2) Gearbox failed in outside lane of A1M. Again no warning, the first I knew of it was the engine red lining.
3) Big end bearings failed. Engine kept going but I had to keep tuning the radio up to blot out the din from the engine. Managed to keep going for the last 50 miles. Made a mental note to buy a bigger radio for the next time.
I guess whether you get any warning depends on the type of failure.