I used the Eitzen Visgage a lot over about 15 years. The one I had came in a great wooden carry case with good closing clips. These are delicate, they do make a mess if the tube which is filled with oil breaks.
They are pretty good, I usually got well within 5% of the eventual UOA viscosity. I used them a lot to detect oil dilution in large diesel engines. Its a lot easier to detect fuel dilution in an SAE 40 than in a multigrade, but if your multigrade is a good one which doesn't oxidise and thicken or shear down (like DELO 400) then you can work with multigrades as well - you just need the 40°C viscosity to check against.
Its been a couple of years since I used one but here are some thoughts.
I think the viscosity comparison it gives is at 40°C.
It works by comparing the roll of a ball in the sample tube against the roll of a ball in a tube filled with a standard oil. Don't tilt it too much, and level if off as the first ball nears the mark.
If you're checking a used oil which is dark, turn the visgage upside down so you can see the point of the ball rolling on the glass tube.
Give the sample tube a good pump when emptying it out, you don't want to leave too much of the last sample in the tube. I used to clean mine out regularly by filling the sample tube with diesel, followed by a few fills/empties with a clean engine oil.
But most importantly, load the sample tube then leave it for 1/4 or 1/2 an hour (the longer the better) for the temperatures to stabilise. You'll get an incorrect reading if your sample oil is at a different temperature to the oil in the standard tube.
If you are dealing with a customer or problem solving out in the field, if you explain that you've got to let the oils reach the same temperature then you get to spend some time talking things over. If you're trying to solve a problem then its amasing how often extra information which will highlight the answer will come out in a relaxed discussion.
[ June 10, 2004, 05:33 PM: Message edited by: SteveS ]