[GMcL]

I've only had two engines that consumed oil between services, both petrol, both turbo charged.
The first required a bottom end rebuild when it started consuming a litre of oil every 500 miles at 14,000 miles, the second a complete new engine after it consumed .85 litres over 6,000 kms. The second engine let go at 21,000kms from new at less than two years old, 1 owner, full service history never raced. The crank and balancer shafts made a break for it out through the sump.

I'd want to know where the oil was going, petrol engines are not oil burners. When they start consuming oil there is something not right.