Having been stripped of a Race 1 victory thanks to a restart overlapping violation, the Briton took third behind first-time race winner Hayden Cooper and rookie Jake Fourace in Race 2 before dominating the final.
The Race 3 result saw Winslow leave the most wins in a season and most points scored in a season benchmarks for the class at 13 and 276 respectively.
“It was the perfect way to end a just about perfect season,” said Winslow after Race 3.
“Obviously we were a bit disappointed with yesterday's penalty and wanted to show our obvious speed which we were able to do in race three. We've had pace all weekend and that was a great way to show it.”
Chris Gilmour underlined his second place in the points standings with second in Race 3 ahead of Steel Guiliana, Nathan Morcom and Forpark National Class round winner Lachlan Marshall.
The wet conditions in Race 2 allowed Cooper to take a dominant 50s victory in his older model Dallara F304, despite a spin on the formation lap.
Cooper and Fourace – who took Mygale's best ever result in a F3ADC race – both benefited from electing to run new wets in the eight lap encounter.
“I was pretty confident going into it, even though I'd never driven in the wet – I just didn't say anything,” said Cooper afterward.
“The car was great and I just did my own thing. It's pretty amazing to have a win amongst this kind of company.”