I have a 1998 subaru legacy outback with 180,000 miles. Much to my dismay this car has been burning a lot of oil... almost one quart every 1000 miles. I was previously using 5W30; after doing some research I read that using a thicker oil could possibly help reduce oil burn (slipping past the pistons). I was also recommended Lucas Oil Stabilizer at my local auto shop. On this last oil change I used 3.5 qts of Rotella 15W40 and 1 qt of lucas oil stabilizer. So far the car has been running great - the check engine light has turned off, and I haven't lost any oil! The car starts up just fine (it MIGHT be slightly slower to start on cold mornings but hardly noticeable). After doing some more reading I have concerns that perhaps I could have been a bit over-zealous with the "thick" idea and the oil I have used plus the Lucas Oil Stabilizer may be too viscous. I am on the west coast and the temperature is not going to be below 45 degrees F (high temperature right now is around 70). Any thoughts? Thanks!