Hi, sorry if this has been covered, it's not easy to search for.
I am looking for recommendations for oil, filters and oil change interval.
We have a 2007 Subaru with the 2.5i NA engine. We bought it well used (to put it nicely), and it has burned oil at a rate of about 3/4 Qt per 1K miles for the last 50K miles, the whole time we've had it. It also makes the oil very dirty rather quickly. It leaks a little oil, possibly from the oil pan, and I think from one of the valve covers, but not too much, no puddles on the driveway. I have been using mostly Mobil 1 5W30 HM in it, but I have also occasionally run Penzoil HM Synthetic and more recently Walmart Supertech Full Synthetic HM. None appear to burn less, but my last change with the Supertech looked extremely sooty at 5K miles, which is my usual OCI. I have used Subaru, Fram, and recently Supertech oil filters.
This last sooty oil change was with a Supertech filter. I took apart the Supertech filter and it's construction seemed good, metal end caps and core, but the filter media in the tiny filter is shockingly small, there can't be a whole lot of surface area there for filtering. I put in Mobil 1 oil and a fresh Supertech filter. I may change the filter out after 2-3K miles this time to see if that helps.
Given the rate at which I have to add oil and how dirty the oil gets, I am considering going to conventional oil to save some money, and going to a 3K OCI. I would like to pick a conventional oil that has a good additive package to handle the soot and not sludge up the engine, and a HM might be good for the leaks I have. I am also considering spending a little more on the filters. I can get Subaru or Wix filters for a few dollars more than the Supertech and I think the bypass pressure settings would match the Subaru specs, the Supertech may be considerably lower. The Subaru filters seem to have cardboard end caps similar to Fram, which is why I gave up on them, but I suspect they would be fine for a reasonable OCI.
What's a good oil maintenance approach for this car? Thanks! -- Jim