Nick Percat led the way in the #17 Team BRM Audi as the race entered its second quarter, however that entry had only stopped twice to that point.
Around 15 minutes after the three-hour mark Percat came in for a third service, handing the Audi over to Am driver Mark Rosser in the process.
Moments later a fourth caution period was called due to the foggy conditions, which prompted a flurry of stops.
As those stops shook out Markus Winkelhock, who took over the #777 MPC Audi from Ricardo Feller, ended up in the lead ahead of Rosser.
However Rosser wasn't second for long, an unschedule stop to fix his rain light dumping him outside the Top 10.
Winkelhock bolted at the restart and was comfortably leading Chaz Mostert in the #65 MPC Audi when the safety car made its fifth appearance at the 3h40m mark as the fog worsened again.
Again the caution triggered stops for the front-runners, Winkelhock and Mostert settling back into first and second ahead of the restart.
The race went green shortly before the four-hour mark, Mostert charging past Winkelhock to grab the lead at Forrest's Elbow two laps later.
The top three, Mostert, Winkelhock and David Reynolds (#24 MPC Audi) then all dived into the pits at the end of that lap to tick off another of the mandatory stops.
That left the #91 Craft-Bamboo Mercedes in the lead with Daniel Juncadella at the wheel.
That car had been running to a fascinating strategy, cycling through the pits 12 times to easily satisfy the nine compulsory two-minute stops.
That meant the entry had more strategic freedom and a huge lead thanks to being able to make faster stops.
Around the 4h20m drivers started to gamble on slick tyres, Dean Fiore the first to do so in the #9 MPC Audi, quickly followed by Broc Feeney in the #888 Mercedes.
Juncadella made a 13th stop for the race right on the 4h30m mark, his lead big enough that he was able to resume with 40-odd seconds still up his sleeve.
The rest of the field made the slicks switch in the laps that followed, helping early adopter Feeney move into second place.
Luca Stolz made it a T8-run Mercedes two-three in third in the #75 entry, which had served two drive-throughs for restart infringements when Kenny Habul was in the car.
Winkelhock, meanwhile, was the last driver on the lead lap in fourth.
Reynolds and Talbot, who took over the #65 entry from Mostert, were fifth and sixth at that point, although Talbot lost more ground when his R8 rolled to a stop on Mountain Straight just after the five-hour mark.
Luckily he was able to switch off and re-fire the car before continuing, however the delay put the entry two laps down. There was worse to come, though, the problem eventually forcing that car into the garage for a compressor change, which took it out of the running.
The leading Mercedes stopped for fuel and a driver change at the 5h20m mark, Kevin Tse resuming with a 20-second lead over Stolz.
It was a margin the German was able to swiftly run down, the lead changing hands right on the 5h30m mark.
Five minutes later Winkelhock got past Tse for second place, however Tse found himself back in the lead shortly afterwards when the two lead cars both pitted.
Jules Gounon jumped back into the #75 Mercedes while Yasser Shahin took over the #777 entry from Winkelhock.
There was a nervous moment for Tse right on the six-hour mark when he glanced the wall coming up to McPhillamy Park.
He seemed to avoid any serious damage though and leads the race by just under a minute over Gounon. Prince Jefri Ibrahim (#888 Mercedes) is third and Shahin fourth.
Watch the race live and free at Motorsport.tv (not available for viewers in Australia and New Zealand).
