recently had oil changed. they used high-mileage. now subaru is smoking

What have we learned ? ?

Make sure they didn’t overfill the crankcase. If that is good what weight and type of oil was used? If you can’t figure it out then have a good independent shop check it over cause this will ruin the catalytic converters.

Oh yes type of oil does make a differance, some years back I had a vehicle come into my shop smoking like crazy, he said he just had it serviced, so I checked it over and the only thing I found was that the engine oil just felt wrong, when you get as old as I am you get a feel for that way fluids act between your fingers, so i changed the oil and filter again and bingo it quit smoking. Still don't know what oil it was .

What is "high mileage"? And, how many miles are actually on your 2003? I ALWAYS recommend using the oil that's specified in the owners manual regardless of how many miles are on your car? Yes, okay, it's exhibiting some issues; the car is nearly 20 years old.. When was the last time you had the car serviced for all other things? Could be a lot of different issues going on here...in my opinion.

Have the oil changed again (at a different shop) and use the recommended oil, not whatever the guy put in last time. If I am not doing it myself, I always check what they are putting in each time. High Mileage oil didn't cause this, the idiot that used whatever grade of oil he had in the shop did.