NavList:

Ed you wrote: You can eliminate clean up completely by lining the Davis tray with a small piece of Saran Wrap (thin plastic food wrap abailable at grocery stores) before you pour in the oil.

What a great idea.  I wish I'd thought of that before I started dabbling with engine oil.  For me, the cleaning up afterwards took longer than the making.  Another problem with oil is you need to cover it when not in use if you want to use the same set-up on several occasions without re-pouring.  Otherwise, you can guarantee that there'll be a tiny spec of dust dead inline with the sight messing up the surface.  DaveP