Well, after much shopping, I found a 05XT, 86,000 miles, one owner, oil changed every 4k miles, and all services at the dealer. Took it for a test drive. Drives great, handles well, new tires, fluids clean, no leaks, etc. I bought it at a used car dealer, but 210 miles later when I got it home, it was pint of oil low? It doesn't smoke, or smell of oil burning. I plan on removing the banjo bolt screens, and changing the oil with Shell T6. My local dealer will do a compression/leak test for $189. Should I go for it? :icon_confused: Any other ideas?
Compression tests are always a good idea, but it may (or may not) give you any clues on oil usage. Vehicles with great compression can still use oil - sometimes quite a bit.
Your vehicle can use oil in a few different of ways - past the rings, leaking head gasket, or leaking onto the ground. Your job is to figure out which. To aid in this task, you might consider removing the under-vehicle cover. IMHO, it's a PITA anyway, but some forum members like it. But, in your specific situation, you really need to have quick and continuous access to the complete under-engine area.
Get organized: Change the oil to whatever brand/grade you plan to use. Change the filter. Check that the drain plug is not leaking. Carefully clean the underside of the vehicle with paper towels or whatever, so any new leakage will be visible.
While under the vehicle, look around the filter area for leaks. Subarus tend to be 'leaky' and the oil cooler sealing ring is a likely leak candidate. It's a cheap enough part - sort of a nuisance to replace - but do-able. Also, look for any other leaking under the vehicle. If you park in a garage, put down newspapers so you can detect any dripping.
Be consistent: Check your oil the same way each time. For example, you drive in with the vehicle hot. Stop the engine, pop the hood, wait 5 minutes and check the oil. Or, you could check it stone cold. Exactly how you do it is probably less important than just being consistent.
Check your coolant: If the head gasket is leaking internally, you might have combustion gasses or oil in the coolant. Serious problem - a new head gasket is really the only fix. I would not rely on stop-leak additives for this issue.
Check your engine seals: Sometimes they leak. A possible fix is 'high mileage' oil (which has seal expanding additives) or else some proprietary additive that causes seals to swell. When you schedule the 105k timing belt service, be sure engine and cam seals are on the menu.
Rings: If your rings are passing oil, you could 1) simply live with it or 2) mark your calendar for an engine rebuild or 3) explore additives like molybdenum disulfide which should reduce oil loss past the rings (and may confer some other benefits). Of these choice, simply living with the usage is by far the easiest and probably the cheapest. MoS2 products like LiquiMoly are worth exploring - but it will take a few hundred miles or more for it to really start working.
Finally, be rational about this problem. Subaru says 1 quart per 1k miles is okay. If you change your oil every 3,000 miles, that's 2 extra quarts of oil added per oil change - not really the end of the world. If you feed your vehicle on MoS2 and reduce this usage to 1 quart per oil change, that savings will pay for the MoS2 (and you'll get a warm feeling and you can join the MoS2 club on BITOG ;-)