Can one top off GC w/ M1 0w-40?

Louisville, KY
I currently have a fill w/ GC at 1100 miles or so. No discernable drop in level yet, but since this boards is beginning to talk me into a longer interval I wonder... At 3000 miles oil changes I never need to top off , but what if I go 6000 miles? I am sure I will, and I have 2/3rds of a qt M1 0w-40 here. Since my sump takes exactly 6.00 quarts I dont want to break open my special ordered cases of GC. What do you guys think, should I used the left over M1 0w-40 as top off? Fred.. [Smile]