Originally Posted by Jordo!

After evaluating several UOA's from other folks and my old Z, I've tentatively identified between 4 and 4.25K to be the ideal OCI.

It's hard to imagine waiting til 5K is making that much of a difference, but it's possible, and the viscosity was a bit low relative to desired values.

Try around 4K exactly for the next one and see if lead either goes down or at least remains stable.