xwd transfer case

2015 Opel Insignia (aka Buick Regal), same drive train as Saab 9-5 NG (2010-11) 1st drain, 41600 Miles/ 67000 km, GM OEM fill (GM 93165383), ~0.6L used - replaced with Redline GL5 75w90, as recommended by Redline. Front Power Transfer unit/ transfer case. Wear + additives PQ Index 136 Iron...