Thanks,

Car has not been abused and the oil was changed every 12,000 km (~6,000 miles) km or so. PVC seems OK. I think the oil control rings are broken, stuck, or soft...

Dealer is saying the oil was not changed often enough and that they will likely refuse the warranty claim unless I can produce more oil change receipts. Do they have a right to do this? Oil change intervals are "recommended" not required...?