It marked the 42nd career win for van Gisbergen, who will leave the rural New South Wales circuit with a maximum 300-point haul.
"That's a team win, a strategy win, the car was awesome," he said. "Unfortunately we can't battle on track, so we had to try and win it in the pit lane and we did.
"That middle stint was insane. It was so cool to get such a good car and push in clean air.
"[Engineer David] Cauchi just asked me to make the gap; normally you're managing managing tyres and everything.
"I had eight laps to do on those tyres, so just qualifying laps the whole time.
"Watching [Waters] get smaller in the mirror was pretty cool.
"It's awesome, and also to have fans here again as well. To win here with an atmosphere is awesome as well," he said.
Van Gisbergen will carry a 33-point lead over Mostert into the next round, with Winterbottom 69 points adrift in third.
Fourth-placed Davison is the only other driver within 100 points of van Gisbergen, with Whincup fifth, 102 points down.
The Supercars Championship field will return to Victoria for the Penrite Oil Sandown SuperSprint across March 21-22.