is a test developed by Exxon to measure the corrosiveness
of lubricating oils. A small lead panel of known weight and a copper panel
(as catalyst) are attached to a spindle, which
is immersed in a tube of the lubricant and rotated. Air is introduced at the
bottom of the tube and allowed to bubble up through the sample. The weight
loss by the lead panel after a specified period of time is a measure of the
corrosivity of the oil.