I don’t think there would be any lasting damage from overflowing oil for a 10 mile drive, unless it was super overflowing, how did they forget to drain the oil before pumping the extra 5 quarts, or drain the oil, one guy added 5 liters. , went on break and then another guy added 5 liters to get your car out the door. At that kind of level, the camshaft can end up burning oil, and on a flat/boxer engine, the pistons are flush with the crank, so the valvetrain won’t drain from the head.
Did you happen to check the tape before the car pulled over?
You will call SOA to let them know of this situation and your concern about the safety of the car and the longevity of the engine due to the damage, and if there is anything they can do to help resolve your concerns and give you confidence in the long-term machine.
While you get a 5 year 60,000 mile powertrain warranty, Subaru offers an extended 10/1000 warranty and in some cases Subaru has given it to customers for free after something has happened to make the car potentially have shortened lifespan.
