[asphaltgambler]

There are problems across all makes with the 'variable' displacement. GM / LS series suffers piston oil ring sticking and sludge. When running the cylinder that 'deactivates' runs suddenly cooler as there is no fuel and little pressure. But hot oil is still splashed up onto the cylinder wall but now the oil ring ( lowest) is 'cold'. Frequently it leads to sludge build-up. Then slowly the sludge starts to pack the oil ring / land and then prevents ring 'float' and drain back. Soon liquid oil is getting past the oil rings and creeps into the combustion chamber. Rapid oil consumption, plug fouling and emissions system damage follows.