Chasing after his seventh V8 Supercar championship, Jamie Whincup made a great start by taking pole position for both Saturday races.
The start of Race 1 was abandoned after Scott McLaughlin's car suffered an oil pump failure on the warm-up lap.
Mostert retired after hitting the wall at turn 8, while Whincup fell down the order due to a punctured tyre.
Former V8 Supercar champion Marcos Ambrose stole the spotlight on Sunday by qualifying for the Top Ten Shootout.
Seven support series raced during the weekend, including the Australian debut of Robby Gordon's Stadium Super Trucks.