I know there has been considerable discussion about oil for Hyundai turbos, and being a first-time Hyundai owner, I wanted to make sure I'm doing the right thing for my 2018 Elantra GT Sport. When I took it in for my first (complimentary) change, I asked the Service Adviser if 5W-20, as indicated by the windshield sticker, was put into the car. "Yes, that's the right oil for your car." When I pointed out the oil filler cap and the owner's manual calls for 5W-30, I was told "that's wrong." Having owned four or five cars with turbos, I have never seen one with less than a 30-weight specification. Having always done my own oil changes, I immediately drained the dealer oil and replaced it with 5W-30 Pennzoil Platinum Full Synthetic and a new OEM Hyundai filter. BTW, the Pennzoil was the only readily available one I found that says it meets the ACEA A5/B5 classification.