Cutting for a friend. He is possibly the biggest oil thicky fan out there. 2 quarts Lucas and 5 quarts M1-HM 10w-30. Ran for 7-8K miles.
Vehicle: 2002 Chevy 2500 8.1L 251K miles.
Filter looks good but I sure don't understand that oil choice. Why not just run a 15-40 HDEO if he likes thicker oil?
This blend has a KV100 of about 40 cst, a good distance north of the 70wt nitro draggers use... I don't think anyone makes stuff this thick.
Using the widman calculator, M1 HM 10w-30 (KV100 = 12.0 cSt) x 5 quarts and Lucas Oil Stabilizer (KV100 = 124 cSt) x 2 quarts (71% M1 blend) comes out to 20.98 cSt.
It's still double the viscosity that engine needs. It also dilutes the additives heavily. The zinc and phosphorus levels in that mixture would be <600 ppm. Pretty much take all of the additives in M1 HM 10w-30 and slash them by 30%.