Sami Vatanen, Kyle Palmieri and Ryan Getzlaf scored to give Anaheim (20-6-5) a 3-0 lead, but the Ducks needed an empty-net goal from Nate Thompson to put away the Oilers (7-18-5), who have lost three consecutive games and 14 of their past 15.
"If you look around the League, there are a lot of three-goal leads and two-goal leads where the other team catches up," Ducks coach Bruce Boudreau said. "I think it's because it's difficult to keep your foot on the pedal for 60 minutes and just keep going and keep going. But it's something that hopefully before Game 82 is done, that we learn how to do. We're going to have to play 60 solid minutes if we make the playoffs."
Anaheim's previous 12 wins were by one goal and it has a 15-0-5 record in one-goal games this season.
The Ducks scored twice 50 seconds into the second period of their sixth consecutive win.
Palmieri and Getzlaf scored 43 seconds apart to chase Oilers starting goaltender Viktor Fasth, who gave up three goals on 12 shots.
"You couldn't ask for a better start to the second period, two goals in a minute," Palmieri said. "But we let our foot off the gas and it's a bad habit that we have to get out of. We have to put teams away.
"It's tough to say what happened and what turned off in our game, but we got away from what we were doing to make us successful and you can't do that. Especially on the road when teams can build momentum with just one shift."
"They came out very hard and we came out flat, we were watching," Oilers left wing Taylor Hall said. "I feel like I've said it way too many times this year, it's a couple of shifts that kill us, a couple of shifts that put us behind the 8-ball.
"You don't see too many teams come back from 3-0. Even though we played very well after that, it's just too hard, teams are too good now."
Ducks goaltender Frederik Andersen made 21 saves for his 16th win of the season. Andersen has started 17 games in a row.
The Ducks took the lead at 4:56 of the first period when Sami Vatanen snapped a shot past Fasth from the top of the faceoff circle. The Ducks outshot the Oilers 10-3 in the period.
Palmieri scored seven seconds into the second period to extend the lead to 2-0. Ryan Kesler won the opening faceoff back to Vatanen, who spotted Palmieri splitting a pair of Oilers defensemen. Palmieri went in on the set play and beat Fasth on a breakaway.
"We've been waiting to try it for a couple of games, and lucky enough, [Kesler] won the faceoff clean and Sami made a great pass and I was in all alone," Palmieri said. "A lot of things have to happen in order for that play to work. We've tried it a couple of times before and something always seems to go wrong. It was good to get off to a good start, but obviously we would have liked to play a little better in the rest of the second period."
Getzlaf scored 43 seconds later to put the Ducks up 3-0, taking a drop pass from Rene Bourque and beating Fasth with a long wrist shot.
Fasth was making his second consecutive start for the Oilers, who lost the first game of the home-and-home 2-1 at Honda Center on Wednesday.
Pitlick scored for the Oilers at 15:24 of the period, collecting a puck along the boards after a turnover by Ducks defenseman Cam Fowler, a result of a hit by Oilers center Ryan Nugent-Hopkins along the boards.
"In the first period I thought we looked tired, it was our fourth game in six nights," Oilers coach Dallas Eakins said. "I'm not using that as an excuse though. You have to play the game, have to manage the game. We got out of the first period and dodged a couple of bullets and we had settled in. Going into the second we challenged a couple of players that we needed more out of and gave them a chance to start the period and the response was not there."
Petry cut the lead to 3-2 on the power play at 12:40 of the third period. The defenseman took a pass from Hall at the blue line and the shot hit the stick of Ducks wing Devante Smith-Pelly and deflected up over Andersen.
Thompson scored into an empty net at 19:43.
"It got interesting when I take a late penalty again and they score and are within one," Getzlaf said. "We knew we had to tighten down and play better hockey. I thought we did it for the most part in the second period. I thought we responded after that. But you definitely don't want to let up the way we did in the second period."