DERG
Oil Consumption
For engines that use labyrinth seals, oil consumption is largely dependent on vent air-flows and oil temperatures. As the seals wear, oil consumption rates go up. Depending on the engine design, typical consumption rates would be in the range of 0.05 to 0.30 gallons (0.19 to 1.14 liters) per hour.
SFC - Trent verses GP
One of the things that strikes me on the SFC situation is the difference between a well designed two spool engine verses a three spool design. IMO, a bare two spool engine in a test cell will have better SFC than a three spool RR engine every time. The reason has to do with the more efficent HPT of a two spool engine. It is a different story on wing. The shorter three spool engine in a shorter nacelle makes up the difference of SFC shortfall in the test cell. The reason is less aircraft drag. However, looking at the Trent 900 & the GP7200 on the A-380 wing, a longer nacelle is used for both engines and the shorter engine advantage of a three spool engine is lost. I do believe, at this moment, the GP7200 does have a SFC advantage over the Trent 900 and RR is working the issue. This may also be an issue on the Trent 1000 verses the GEnx on the B787.
Just some thoughts,,,