Last week, Oakley succeeded in smashing the 4-minute mile, after trying unsuccessfully twice on an indoor track during the US winter.
"I knew I could do it if I just ran a good race, and everything kind of went to plan and there was a good pacemaker," Oakley said.
"It's a big milestone, I guess. I don't think it's quite sunk in how cool it is. It gives me a lot of confidence when you run a good time like this."
The middle-distance runner first shone on the track when he switched from a bunch of sporting codes he was good at including soccer, cricket, squash and golf, at age 16.
Under coach Gareth Hyatt, a former New Zealand track champion, he began winning regional and national races in the 1500m.
Oakley, who has three younger brothers all with sporting abilities, said his squash-champion mother and father John Oakley encouraged the boys to play sport but didn't push it on them.
"I played everything. The others took up squash a bit more than I did."
Oakley's new American friends did not know about his mother's historical sporting achievements.
"Half of them don't even know what squash is," he said.
He will return home this week for the North American summer to gear up for the crosscountry season.
He aims to run a "good mile indoors" and make the nationals for the 1500m, which he just missed out on last year.
Eventually he hopes to follow in the footsteps of Kiwi athlete Julian Matthews, who also went to Providence College, and is now in the 2014 Commonwealth Games team for the 1500m at Glasgow next month.
Dame Susan said she was delighted with her son's achievement.
"He's an extraordinarily diligent young man, but I don't know much about running and I see how hard it is so I just think, good on him. I think he'll give it a real crack to see how far he will go."
Of her other children, Alex, 19, plays representative cricket, Josh, 18, is in the New Zealand junior boys' squash squad, and Jamie, 16, is also a talented squash player.
"It would be an understatement to say we're a sporting family but they do enjoy it as much as anything else and that's what it's really all about."
John Oakley said his son was enjoying "terrific competition" through being a student at Providence.
"He wanted to be as good a runner as he could possibly be and he felt, like we did, he would get that intense competition they get, running at a top event every weekend around America."
He said his wife was "hugely proud" all the boys had inherited their sporting talents from her.
"I played a bit but Susan was the champion."
