I have a 2017 Niro. Two weeks ago the oil pressure light came on, then went off, came back on again for a few seconds and then went off again. I took it to my mechanic who found nothing wrong. He change the oil and filter. The same thing happened again a week later. the first time was in town, the second time was on the freeway at 70 mph. The dealer now will change the oil and filter again because they couldn't find any cause any suggestions?