I was given 5 cases or Valvoline premium blue geo m-85 NG engine oil 15w40. It came from a cummins tech and is used in gensets it is cf-4 rated does anybody know how this corresponds to the older Cj4 diesel oil I was told it is pretty much a low ash diesel oil used in CNG and LPG engines for long drain intervals. I want to run it in my 2009 duramax if it meets or exceed Cj4 if not it will go in a friends oil burner heater tried to sell it on Fb marketplace no takers. I emailed Valvoline on their site but have got no response. Just curious if any idea's who to ask. the product code is 875539.