New engine - oil change recommendation - 2014 Sonata

My 2014 Hyundai Sonata had its engine replaced under warranty last year, and it has driven about 3500 miles since then. The dealer used 5W20 Synthetic Blend oil.

I’m looking for advice on:

  1. Should I continue using the 5W20 synthetic blend? Any recommended brands?
  2. How many miles should I wait before changing the oil? The service advisor suggests waiting 5000 miles.

I appreciate any advice you can offer. Thanks in advance!