He joined Dutch club FC Utrecht in 2010, making over 100 appearances for the side before moving to England to play for Ipswich Town in 2015.

Oar previously played at Palm Beach Sharks football club on the Gold Coast and eventually the Queensland Academy of Sport, where he was picked by Brisbane Roar.

[5] In his second A-League appearance, on 28 December 2008, Oar scored a late free kick to secure a win over Wellington Phoenix.

[7] In January 2010, Oar signed with Dutch agent Rob Jansen and was linked with a move at the end of the 2009–10 season to Eredivisie squad Feyenoord Rotterdam and trained with FC Utrecht with fellow Roar players, Michael Zullo and Adam Sarota.

He was awarded 10th place in the Voetbal International Eredivisie player of the Year standings and was linked with clubs such as Benfica and Celtic F.C.

[15] After a further substitute appearance against Blackburn Rovers in the Championship, Oar made his starting debut for Ipswich against Huddersfield Town.

[19] In February 2017, Oar scored and assisted in a 2–0 victory over Carlos Tevez's Shanghai Shenhua, to qualify for the Asian Champions League.

[20] Oar made his competitive debut for APOEL in a UEFA Champions League qualifying win over Dudelange on 12 July 2017.

[23] On 22 December 2009 Oar was named in the Australian national team squad for the 2011 Asian Cup qualifier against Kuwait but did not play.

[25][26][27] His performance in this match led to comparisons to Harry Kewell and the potential for Oar to succeed the Australian great, and resulted in his selection in the 2010 FIFA World Cup squad.