OK... let's get to the theory part !!!! Contrary to popular opinion, engines are designed to use oil. This is necessary for proper lubrication of the rings, and the "oil ring" is designed to remove excess oil from the cylinder wall, while leaving a thin film for the compression ring/s to run on. This prevents scuffing of the ring on the cylinder wall, aids ring sealing, and assists in heat transfer from the piston crown to the cylinder wall. The film of oil is evaporated/burned during the combustion process. So far so good
Engine manufacturers typically quote Specific Oil Consumption figures for new engines of between 1.0 g/kWh (heavily loaded) to as little as 0.1 g/kWh for a lightly loaded engine. Here we will take 0.3 g/kWh as a typical figure for a 100 kW family car. Consider this car traveling at a steady 100 k/h. It will probably be making about 25 kW.
This gives an oil consumption of 25*0.3 = 7.5 gms, and the car will have travelled 100 km. Under these conditions, after 10,000 km the engine will have used 10,000/100*7.5 = 750 gms of oil. At a SG of (say) 0.8 this will be 750/0.8 = 0.937 litres for a brand new i.e. "good nick" engine.
Of course, not everyone drives at a steady 100 k/h for 100 hours. So actual consumption will vary +/- according to conditions. Some may appear to use little oil due to lube oil dilution with fuel under cold running/short trips. But this does not mean the engine is not using oil. Lube oil dilution can lead to bearing and corrosion problems.
Now.... back to what you were doing
Cheers.....
jondee86