[raceteam]

Does the usage pattern change at all? The most common reason for sudden apparent oil consumption is a car that gets used for regular short trips, then goes on a longer one and uses a litre of oil. What is happening is not sudden oil use on the longer trip, but the motor gets warm enough to evaporate condensation from the crankcase that it can't do on shorter trips. On each short trip, a small amount of oil is used, and a small amount of condensation appears, so the oil level on the dipstick look unchanged, even though it has dropped a bit. Get the car hotter than it usually gets, all the condensation evaporates again, and it looks like a very sudden drop in oil level.