Repairing for the neglect by previous owner (Hyundai Elantra)

My wife bought a used 2011 Hyundai Elantra, 110K miles, from a friend.
There weren't any accidents with the car and since she was a friend, we trust
her that there are no known issues. We did not do any inspection either. She
had done an inspection 1 1/2 years back when she purchased this car
(used) form a auto sales shop.
The car runs well, no obvious problems. But we learned that she hadn't
changed engine oil in last 1 1/2 years (9 K miles). While changing the oil, the
mechanic said the previous oil level was very low. We are also not sure if the
owner before her took good care of the vehicle.

What can I do to repair any damage caused by above mentioned neglect so
that the car runs well for a long time?