My WRX (turbo) consumes ~0.5 quart and my OCI is 5k. Consumption only starts when I am 3500 miles into the OCI though. I have tried many types of oil (Redline 10w-40, Mobil 5w-40, Mobil 0w-40, and Chevron 10w-40) and they all behave the same way. I have also done UOAs and they came back normal. So my question is, is non-linear consumption common/normal? Why does it behave that way?