The first number in a multi-grade only references the minimum temperature for cold start pumpability, hence the "W" stands for winter.
0W-xx = -35°C
5W-xx = -30°C
10W-xx = -25°C
15W-xx = -20°C
20W-xx = -15°C
0W-40, 5W-40, 10W-40, 15W-40, 20W-40, and SAE 40 are all 40 grade oils (KV100 = 12.5 - 16.2 cSt) at operating temperature.
I still stand by the Mobil 1 FS 0W-40 recommendation without the Rislone. You don't need a lot of ZDDP. M1 FS 0W-40 contains ~1000 ppm which is more than sufficient. More ZDDP than necessary doesn't add more wear protection, just increases the side effects of ZDDP.
Expanding on what I said earlier, oil formulas are a careful balance to ensure no one additive overpowers another. Dumping in a foreign supplement will throw off that balance. Increased TAN, reduced service life, and loss of synergy with other additives are all risks from a condition known as additive clash.
Same with the MoS2. That's an outdated solid particle friction reducer that's far surpassed in effectiveness by modern liquid MoDTC at much lower concentrations. The 60-80 ppm MoDTC is doing far more than even 600-800 ppm of MoS2 would. In fact, the MoS2 is likely doing nothing at all.