Real important emergency question. Help! Help!

and split the difference. Then later, when you have time, just loosen the bolts and rotate the vial,until it reads the same coming as going.
Its sorta like fixing the daym square you've been using all these years and nothing ever comes out right. Or the stinking table saw that cuts nothing but wedges,binds up, and every board gets at least one burned edge.
Or like the weatherman; he can't get the day right if he's having his morning coffee on the porch looking at it. How does that guy live with himself being wrong every single day of the year. My wife's knees are more accurate,sheesh! Well, being wrong 100% of the time must be worth something.........
Or like the micrometer in your sidebox that is 2/10s off, but if you leave it on the bench, then it's only a tenth off,lol.
As to the POs original question, I doubt it matters but I buy only the softest white stuff, cuz my azz is worth it.