"I had a good shear in the heats," Oldfield said.
"But the final's sheep were pretty tough. I had a rough one to start, and it took a bit to get back on track."
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The 28-year-old from Geraldine now aims for a second consecutive Corwen Shears title in North Wales on Saturday.
He will then head to the Falkland Islands for a month's shearing, before a holiday in Italy.
Oldfield will then return home for a reunion with Allflex New Zealand World Champion teammate Tony Dobbs.
He will be in time for the New Zealand Spring Shears in October on the second weekend of the 2019-2020 season in New Zealand.
Oldfield shares a blade shearing gear and training business with his father Phil, who came third at the 2017 World Championships.
Oldfield said his big win over defending champion South African shearer Mayenseke Shweni in the World Championships final in Le Dorat earlier this month had sparked more interest in his family business.
"We have already had a couple inquiries for shearing schools overseas," he said.
Oldfield has packed all his winning into the last three-and-a-half years, including the rare clean sweep of the open blades titles in the UK at the Royal Bath and West, Royal Ulster, Royal Highland and Royal Welsh shows.
He said his dream of winning probably goes back to competing in the Golden Shears All Nations blades shearing at the 2012 World Championships in Masterton.
He didn't make the final, but he did get the chance to see the powerful South African domination in the final win by Shweni and teammate Zweliwile Hans' fourth world final win 24 hours later, albeit both in times averaging over three minutes a sheep.
"I think I set the goal then," he said. "Then I started to feel like I had a real chance about two years ago when I started to get some stronger wins."
Asked for the secret after ending a South Africa and Lesotho World blades titles domination dating back to 1996, Oldfield said: "Being focused and making a point of getting practice in even if it's inconvenient. And travelling to be adaptable to different breeds of sheep."
While he started learning to blade shear at the age of 13, he had until his 2016 trip to the UK been out of New Zealand just once, as an Under 20 New Zealand axe sports representative in Australia, and was still to have significant success in shearing sports.
But he soon found the environment to his liking, with a quickly achieved treble of his first wins in open blade shearing, junior machine shearing, and, to complete a possibly unprecedented three-disciplines milestone, in woolhandling.
He says he's excited about the prospects for the next world championships in Scotland in 2022, but there is much more imminent excitement to attend to.
He wonders if his parents are more excited about the wins in France than he is, and said:
"I'm looking forward to celebrating with some mates when I get home."
Result:
Royal Welsh Show Open Blades Shearing final (6 sheep): Allan Oldfield (New Zealand) 14min 12sec, 81.433pts, 1; Gareth Owen (Wales) 17min 42sec, 87.267pts, 2; Elfed Jackson (Wales) 16min 10sec, 90pts, 3; Rheinallt Hughes (Wales) 18min 18sec, 94.233pts, 4; George Mudge (England) 18min 48sec, 99.733pts, 5; Adrian Davies (Wales) 20min 13sec, 116.317pts, 6.
