Van der Linde drove home the win for the Meuspath-based squad after 159 laps, equalling the race's distance record.
As ever, the race was not without drama with several contenders disappearing from the frontline before nightfall.
After surviving the night, the Phoenix Audi still had two opponents to defeat in the form of the two GetSpeed Mercedes-AMG GT3s, the #3 car of Adam Christodoulou, Maxi Gotz and Fabian Schiller and the #4 entry of Maro Engel, Jules Gounon and Daniel Juncadella.
The #3 car emerged as Phoenix's fiercest opponent on Sunday morning. Christodoulou and Schiller brought their car within striking distance and were already on the tail of the Phoenix Audi when the weather gods intervened in the fight for victory with three hours to go.
GetSpeed had the strategic disadvantage by pitting one lap before Phoenix. When the floodgates opened in some places over the track, the Mercedes was on slicks. That turned out to be the wrong choice, with Phoenix putting on cut slicks one lap later.
That allowed van der Linde to build up a cushion that ballooned to more than a minute, Gotz being powerless to advance on his treadless rubber. The Audi squad then coolly managed its lead to the finish.
The second GetSpeed Mercedes secured the last place on the podium in third.
The Phoenix Audi survived an early scare on Saturday when Vanthoor clashed with his older brother Laurens in the title defending Manthey Porsche. After tapping his brother side to side, Laurens Vanthoor crashed hard at Dottinger Hohe, forcing Manthey to retire early.
