The teams have played three games in their series. All three have gone Over with 10, 9 and 7 goals being scored. Perhaps the streak ends here. But I'm going to keep riding the Over. These are two offensive-minded teams. Leon Draisaitl and Connor McDavid are superstars and at the top of their games. Neither team has featured good goaltending.
The Blackhawks live and die by attacking and being aggressive. This can lead to mistakes. But they are not all of a sudden going to get cautious. So the pace should remain fast. 
The Oilers have scored at least 3 goals in 12 of their last 17 games. 
It's not difficult to envision each team scoring at least three goals.