I've ran regular cheap GL5 gear oil in the rear till 420,000km on the original rear diff in my DSM. I finally smashed it last year on a launch with the car making 860 AWHP/ 700 ft lbs. That was shear power that broke it. I believe in non synthetic fluids for the driveline in a DSM. My DSM is a prime example of it and you will never see me run Redline fluids, nor do I recommend it for any DSM or Evo transmission that I build. Every transmission builder will have their own opinion 😊