The first thing I would do is check the oil level and top off with anything...
Then I'd do a couple of short 2000 mile OCI's with either Pennzoil or Quaker State conventional, or just about anything else. Then maybe gradually move to a 3000-5000 OCI. You could eventually try a synthetic high mileage like Mobil 1 or Valvoline MaxLife syn, but I'd wait at least a few months to get a baseline of what the car uses. Also change the PCV valve, if there is one, immediately...
Then I'd do a couple of short 2000 mile OCI's with either Pennzoil or Quaker State conventional, or just about anything else. Then maybe gradually move to a 3000-5000 OCI. You could eventually try a synthetic high mileage like Mobil 1 or Valvoline MaxLife syn, but I'd wait at least a few months to get a baseline of what the car uses. Also change the PCV valve, if there is one, immediately...