"Well Jaba lets deal with a fact or two -
My Rotax 912 ULS contains 3 L of oil, which I change at 50 hr intervals. I have never had to add oil between services in its 850 + hours to date.
It uses about 12 L /hr @ 100 knots, can loiter at 60 knots consuming about 8 L/hr and if I ask it, it will do 120 knots on about 17 L/hr. It prefers ULP but at a pinch can dine on AvGas.
It is smooth running and quiet (compared with even a lawn mower, let alone almost every other aircraft engine).
Its seems to deliver power without effort, from sea level to 10,000 ft (my legal limit).
I did have to replace the "sprag clutch" probably from using under-powered battery's but other than this the engine has never been opened and only routine service items replaced.
I expect it to be still motivating my aircraft at 2000 + hrs. "on condition"
500 ml oil.
6 litres an hour fuel consumption, at 100 mmph, VNE 140. (in a dive)
SHAKIEST of all the motors.
All of 35 HP (Hand-cranked ).