2008 Subaru Outback Owner's Manual - Page 373

Maintenance and service 11-27 If the oil level is below the bottom edge of the hole, add oil through the filler hole to raise the level. CAUTION . Be careful not to spill rear differential gear oil when adding it. If rear differential gear oil touches the exhaust pipe, it may cause a bad smell, smoke, and/or a fire. If rear differential gear oil gets on the exhaust pipe, be sure to wipe it off. . If the vehicle requires frequent refilling, there may be an oil leak. If you suspect a problem, have the vehicle checked at your SUBARU dealer. SAE viscosity No. and applicable temperature & Recommended grade and viscosity Others 1) Filler plug 2) Drain plug 3) Oil level Each oil manufacturer has its own base oils and additives. Never use different brands together. Oil grade: API classification GL-5 Remove the plug from the filler hole and check the oil level. The oil level should be kept even with the bottom of the filler hole.