Oswalt threw eight dominant innings and Houston collected 12 hits in a 5-0 victory over the Milwaukee Brewers on Wednesday night.
Oswalt (3-6) walked one and allowed four hits, including doubles by Ryan Braun in the first and fourth. He struck out nine of his final 16 batters while handing the Brewers their 12th loss in 15 games.
Any speculation that the trade talk was bothersome was quickly resolved.
"I'm going to do my job, try to do my job every time I go out," Oswalt said. "It doesn't affect me. The guys came out and gave me a lead, and I was able to hold on to it."
Oswalt said his mechanics were a little off in the first three innings despite being staked to a three-run lead.
"I was worried about giving them up," he said. "I kind of caught my mechanics in the fourth and was able to hold on to them today."
He worked out of the Brewers' best threat in the fourth. After giving up Braun's hit and walking Prince Fielder, Casey McGehee and Corey Hart struck out swinging and George Kottaras took a called third strike.
"When you start threatening, he comes back with something extra," Brewers manager Ken Macha said. "It was a pretty dominating performance."
Brandon Lyon got three outs to finish the five-hitter.
Oswalt's 2.35 ERA is one of the lowest in the NL, and he came in tied for the major league lead with nine quality starts. The right-hander also had the league's lowest run-support average (2.07).
"He was in control the whole way," Astros manager Brad Mills said. "His mound presence was outstanding, and I think he answered a lot of questions from a lot of people."
"We got them early, and it gives you a little more freedom to throw different pitches in situations," Oswalt said.
Oswalt, 32, had his agent contact owner Drayton McLane last week and request a trade, if the team continues to slump. The Astros might be reluctant to make a deal since the last time Houston lost 30 of its first 45 games was in 2005, when a staff anchored by Roger Clemens, Andy Pettitte and Oswalt reached the World Series.
Oswalt, whose contract expires after next season, isn't sure history can repeat itself and would like to bring his experience to a contender. He is willing to waive his no-trade clause for a chance at getting back to the World Series.
The NL-worst Astros (16-30) came in with the major's lowest batting average (.227) and fewest home runs, extra-base hits, runs, walks and RBIs.
Houston snapped a three-game losing streak and has won five of Oswalt's past six starts against Milwaukee.
The Brewers hoped Narveson (4-2) could go deep into the game to save their overworked bullpen. But Vargas started the fifth after Narveson made the shortest of his six starts since coming out of the bullpen late last month.
"Narveson didn't have command of any of his pitches, really," Macha said.
Lance Berkman, who had three hits and a walk, made it 5-0 with a run-scoring single off Vargas.
Trevor Hoffman pitched a scoreless seventh for Milwaukee as he works to regain his closer form. He has blown five of 10 save chances this season.
Brewers C Gregg Zaun, who is on the 15-day disabled list with a right shoulder strain, told the Milwaukee Journal Sentinel before Wednesday's game that an MRI revealed a torn labrum in his throwing shoulder. He said that it was "50-50" whether he would return this season. ... The Astros are 19-9 in Oswalt's 28 career starts against Milwaukee. ... Milwaukee dropped to 5-15, the majors' worst home record.