Vehicle: 2013 Nissan Juke SV, 1.6L turbo with DI - vehicle is leased, so please don't tell me to use synthetic as Nissan does not spec for it in the manual and the car will be returned at the end of the lease. OCI: As per manual, 5W30, every 6000kms (3750 mi). Current mileage: 27000kms (half way point of OCI). Oil changes have been performed by both the dealer and myself. 5W30 conventional always used. Most recent oil change was dealer-installed Mobil 1000 out, Motomaster Formula 1 conventional (Formula Shell) in by me. I've noticed that the currently installed oil started to darken very quickly (even before 1000kms of use) and now it is getting very, very dark. Not black, not gooey or smelly, just dark. Is it that the previous Mobil 1000 was a poor cleaning oil and that the Motomaster (Shell) is just doing its job? Or is the turbo with direct injection beating the [censored] out of this current oil?