Hi I hear you. Oil changes in this case Synthenic I have a three years of records of making the oil changes per Volvoline between 3-4K. Mechanic @ the shop showed me the cam/burn spots and did say the crank was oil starved. Really did know if the was any further test such as oil residue (if any) to send to a test area. This to see if the oil did break down. Also at every oil change the mech showed me the dipstick as being full.