disappearing oil

On my 2001 3.5l Aurora with 55,000 miles I am needing to add a quart of oil about ever 3 months or so. Usually about 70% of the way through the oil life cycle according to the car's computer.

The question is, where is the oil going? I am using 5w30. There is no oil on the garage floor and the exhaust looks normal, no smoke or smell.

Could it be burning oil but just at such a slow rate that it isn't showing in the exhaust?

Thanks,
Lou

Northstars in general are known to use a bit of oil. I'm not so familiar with the 3.5l version, but since I heard it called a 'shortstar' it should have many of the same features... and faults. You could try 10w30 for starters. It's actually better during the hot months, at least according to my little graph in my owners manual (for a 4.0...). I know my oil consumption goes up with the thinner oil. That slow to get though a quart and you might not be able to see any blue smoke.

Another thing you can do is actually look under the car. I, for example have a slight oil leak either from where the halves of the engine block are pressed together or due to porosity in the aluminum leading to seepage. Either way, there is oil on the bottom of my engine that only seeps while the car is running and hot, and always seems to get blown back and away. I have no rust on my undercarriage either :). I've never seen more than 1 or 2 drops anywhere I've ever parked, yet I use at least as much oil as you described.

The long and short of it IMO is unless you've still got warranty until 60k or something, don't sweat it and just keep your oil topped off.