I think this has been asked before, but let this thread host the question since I cannot dig it back up. Lets talk about a blender blending a line of oils (eg. "GTX", "Daily Protection", "Super 5000", "Modern Engine", ect.) (n=1; talking about one of these lines) This blender offers this line of oil in different grades (0w20 vs 5w30 vs 10w40 vs 20w50, ect.) Would it be typical for all grades in that line of oil to have the same amount of friction modifier added? I'm not inquiring about the exact amount; I understand there is slight variability via batch processing and homogeneity. I am talking about intended amount; do they add more FM to the thinner weights? Going one step further, if (and it usually is, so I understand) the FM they purchase for blending in is just part of a performance package, then do they vary the amount of the package added to the weight it will be with/in?