?? Fresh oil will make little or no perceptible difference to the way the car runs; more likely to have been a software update ....or an air filter..
Not disputing you may feel a difference...but it won’t be from fresh oil after 20 000 miles.
Oil change intervals are 20 K on most modern cars and the latest generation of fully synthetics will easily last this long.
As above, there are many threads on changing the oil after the first 10K to allow for running in swarf etc