My father has a relatively new to him '98 E320 w/ 60K on it.

It has burned a little more than a quart of (synthetic) oil in the last 800 mi.

There does not appear to be a leak - no puddles under the car. No blue smoke when driving.

He drives the car very little. He only uses it occasionally when he takes trips out of town - and probably only 1500 mi in the 8 mo he has had the car.

The first time we changed the oil and it was low we thought it had not been changed by the dealer - and had too many miles since the last oil change.

Any suggestions as to the cause? How to begin diagnosis?

Thanks,
Jeb