A tweak to the schedule saw the opening 30-minute session opened to all drivers in the field, rather than restricted to the Bronze-rated drivers.
On a drying track it was the #75 SunEnergy 1 Mercedes that set the early pace courtesy of a 2m07.290s from Luca Stolz.
As conditions improved the German was able to lower the benchmark to 2m05.782s at the mid-way point of the session.
With 10 minutes to go Ricardo Feller took over at the top in the #777 Melbourne Performance Centre Audi entry with a 2m04.908s.
The Swiss driver then went quicker again at the end of the session, a 2m04.515s cementing top spot for the factory-backed Audi.
The #75 Mercedes ended up second thanks to a 2m04.908s from reigning Bathurst 12 Hour winner Jules Gounon late in the session.
Tony D'Alberto was third fastest in the #6 Wall Racing Lamborghini, just six-tenths off the pace, followed by Supercars regular Cam Waters in the #24 Melbourne Performance Centre-run Audi.
David Russell (#47 MPC Audi was fifth as Fraser Ross (#65 MPC Audi) jumped Shane van Gisbergen (#888 Triple Eight Mercedes) late in the session as they finished sixth and seventh.
Daniel Juncadella was eighth quickest in the Craft-Bamboo Mercedes ahead of Joey Mawson (#17 Team BRM Audi) and Nathanael Berthon (#74 MPC Audi).
The second half-hour session was dedicated to the Am drivers, Kenny Habul leading the way early in the #75 Mercedes with a 2m10.223s.
That didn't last long, though, Bathurst local Brad Schumacher going faster on two consecutive laps in the #74 Audi with a 2m08.619s followed by a 2m07.795s.
The two Valvoline-backed Audis spent the middle part of the session trading fastest times after Yasser Shahin went quickest with a 2m07.754s in the #777 entry.
Schumacher then responded with eight minutes to go with a 2m07.282s to take back top spot.
The pair dipped into the sixes as the session wore on, Schumacher's 2m06.580s edging Shahin's 2m06.782s.
They were then denied the opportunity to go quicker by a red flag, prompted by a car stopping at The Chase with two minutes to go, that was ultimately the end of the session.
Liam Talbot made it an all-Audi top three in the #65 entry, albeit just over a second off the pace.
Martin Konrad ended up fourth after taking over the #75 Mercedes from Habul, followed by Tony Bates (#24 Audi) and Prince Jefri Ibrahim (#888 Mercedes).
Zane Morse was the fastest non-GT3 driver with the seventh quickest time in his Invitational class #52 MARC II Mustang.
James Koundouris was eighth in the #47 Audi as Grant Denyer (#6 Audi) and Declan Fraser (#95 MARC II V8) rounded out the best 10.
From Saturday you can watch all of the Bathurst 12 Hour action live and free on Motorsport.tv (not available to viewers in Australia and New Zealand).
