Gallo finished 3 for 3 with a walk and three RBIs. His five-game homer streak is the longest in the majors this season and tied for second in Rangers history behind Kevin Mench, who homered in seven straight games in 2006.
''I've always been somewhat streaky,'' Gallo said. ''Right now, it's just nothing can go wrong for me, and I'm not saying that in an arrogant way or a cocky way. It's just almost surprising. But for me, I just stayed the course. I knew at some point, things would break out and would happen for me.''
Said Rangers manager Chris Woodward: ''It's pretty impressive to watch. It reminds me of Barry Bonds. I know that's a huge name to throw out there, but when you're seeing a guy this hot, you don't even know what to say. You don't even know what to think.''
Lowe had his second multi-homer game of the season and John Hicks hit his first home run since 2019 as Texas won for the fifth time in six games.
''That felt fantastic because that's a solid Oakland team over there,'' Lowe said. ''To get the pitching performance that we got and the one-through-nine offensive performance, that's a big confidence booster going into this weekend.''
Chad Pinder and Ramon Laureano drove in runs for Oakland, which has lost eight of 12.
The Rangers jumped on A's starter Sean Manaea for four runs on nine hits in five innings, finishing with 15 hits in the game. Manaea (6-5) suffered his third straight loss and his first to Texas since 2017, snapping a six-game winning streak against the Rangers.
''Sean was off his game some,'' Oakland manager Bob Melvin said. ''He battled as long as he could. He gave up some hits. Just didn't have his best command.''
Texas starter Dane Dunning pitched four scoreless innings, allowing three hits and two walks with four strikeouts. John King (6-5) followed up with three hitless innings, allowing three runs (two earned).
Gallo had an RBI single in the first inning. Lowe blasted a solo home run in the fourth and Gallo added a two-run shot in the fifth, his 20th of the season.
Hicks took A's reliever Domingo Acevedo deep in the sixth and Lowe launched a two-run blast off Deolis Guerra in the seventh, his 12th of the year.
Oakland scored three runs in the eighth, aided by a Texas error.
Rangers: C Jose Trevino was placed on the 10-day injured list retroactive to June 29 with a right forearm contusion after slipping in his hotel room Tuesday morning. ... OF David Dahl was reinstated from the 10-day IL after missing 30 games with a left rib cage contusion.
Athletics: OF Stephen Piscotty (sprained left wrist) felt good after a full workout Wednesday and is nearing a return, though he could first require a rehab assignment. ... OF Mark Canha (strained left hip) received a platelet-rich plasma injection this week and is unlikely to return before the All-Star break.
Rangers: RHP Kyle Gibson (6-0, 2.00 ERA) starts as Texas opens a three-game series at Seattle on Friday night.
Athletics: RHP Frankie Montas (7-7, 4.72) takes the hill Friday as Oakland welcomes Boston for a three-game series.
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