By Jim Fitch
Practicing Oil Analysis Magazine
Most of us know that healthy lubricants are generally clear and bright. However, as oils age they can lose their luster, and many become dark and opaque. These optical changes are often important symptoms of impending problems that, if occur prematurely, merit further analysis and corrective action.
However, in other cases they can be benign or simply the result of the oil’s normal aging process. So how do we know the difference, especially without having to perform complex laboratory analysis? Like much in the field of oil analysis, answering such questions depends first on better understanding the nature of the problem.
We can score an oil visually the same way gemologists grade diamonds; by color and clarity. An oil’s luster or brightness is influenced by both of these options.