The natural color of most greases is light tan to medium brown. Manufacturers add dyes to some greases to give them distinctive colors, either for marketing purposes or to make them easy to distinguish for maintenance personnel. The color of grease can also provide some insight in the overall condition. read more
The color of grease can also provide some insight in the overall condition. As grease degrades and becomes contaminated, it usually will start to darken. This darkening, which can be more noticeable when compared to new grease, may be a sign that the grease has reached the condemning limit. read more
The bearings are mounted in a common housing and use ring oil-lubrication with bronze oil rings submerged into the bearing oil sump. Figure 2 Within a period of only a few months, a number of field reports of black oil formation were reported. read more
First off, I did do some searching, seemed like several poeple have differing opinions on what turns oil black. The reason I ask is because someone made some comment like"I looked at the oil and it was so dirty that I immediatly had to swap it out" For some reason the use of 'dirty' in regards to someone looking at black oil is now one of my newest pet peaves. read more