Arzani, who played for the Socceroos at the 2018 FIFA World Cup in Russia as a 19-year-old, has been loaned out to Utrecht by his parent club Manchester City after two injury-hit seasons with Celtic.
And Oar, who played 105 matches for Utrecht from 2010 to 2015, said he was delighted for the young star who is one of the finest talents to emerge in Australia in a decade.
"When I found out that he was going to Utrecht I was excited... not only for him but for the club too because they are getting a very good player," said Oar, who will play for new A-League club Macarthur FC after a solid season with the Central Coast Mariners.
"This is a great move for Daniel because Utrecht are a good club and the sort of organisation that will not lose patience with their players if success does not come instantly for the club.
"When I went there I was 18 and rather inexperienced but I knew that they liked to give young players a go and they had a lot of patience with me. They understood that players who come from the other side of the world need time to adjust to a new football culture.
"It is not so easy to hit the ground running immediately and I'm sure they will give Daniel enough time to settle because in Holland it is not as cut-throat as in other leagues.
"Daniel will enjoy it there and I have no doubt that he will hit it off in the Eredivisie straight away because he has all the tools and the right mindset.
"Dutch football should suit his style to a tee. I still follow Utrecht. They like their wingers to play one against one with defenders and we all know where Arzani's strength is. It should be perfect for him and his football education."
Socceroos coach Graham Arnold would be delighted with Arzani's move to the Netherlands because, having played there in the 1990s for Roda JC and NAC Breda, he knows that the Dutch football mentality and culture can be hugely beneficial to Australians who are good enough to play at that level.
After five years at Utrecht, Oar left the club in 2015 to pursue other challenges.
His refusal to sign a contract extension did not go down well with the club and for a while he was frozen out of the first-team.
But he has fond memories of the ambitious club and cannot speak highly enough of the organisation that provided him with his first taste of European football in 2010.
"I was there for five years and after that I wanted to move abroad and try a different league," he said.
"I guess they were unhappy with me wanting to leave on a free transfer and I can understand their point of view.
"There is no ill feeling towards the club. I'm still an Utrecht fan and I want them to do well.
"And Daniel will help them do so. He actually is better equipped to succeed than when I got there because he has two years in Scotland with Celtic under his belt."