I don't understand what pistons and rings has to do with oil on the intake side. If it was oil in the exhaust, maybe it could be pistons and rings. My first thought would be to check the PCV valve, but I would be shocked if the dealer hadn't done that already.
I often hear 1 quarter consumption per oil change is normal, but personally I don't buy it. 1.6 is definitely on the high side.
When you say you have oil in the air intake, where specifically are you seeing the oil? The logical thought is the source of oil will be upstream from where you are seeing it.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)