Engine oil OEM Subaru or PETRONAS

My '15 Forester will burn a quart of oil every 1000 miles if I run 0w20.

I switched to 5w30 and it's all good for 5000 miles

Well, some manufacturers do have way shorter oil change intervals than Euro manufacturers. The Subaru severe driving interval is 3000miles/6 months, and I do lots of short trips in a desert climate so I usually try to be around 3-4000 to stay on the safe side for warranty and whatnot.

The 5W30 full synthetic engine oil works the best for a wide spectrum. Its working temperature range is practical for daily use and it costs less than 5W40.

My giulietta 1.4 MA is still reliable at 130k km. Never had any problems with engine always used recommended petronas oil. Had to rebuild my turbo once (at 120k km) it had very little play that made my car burn some oil.