6cylindersovertexas,
Here are some thoughts. Grease is oil thickened with a 'soap', or thickener.
Additives are combined to give it certain qualities that would be required by the application.
Stringyness additives, anti-wear additives, extreme pressure additives...sort of like making cookies.
The color of a grease is just for the consumer or the ad man. I have been buying a grease lately that is a beautiful blue...I like that color.
Color would have no bearing on the purpose or quality of the product.
So the oil in the grease is going to be about the same with all greases...good oil.
The soap, or thickener is what is different. There is Moly, Poly-Urea, Lithium and probably tons more.
Each one of these soaps has it own characteristic. Some are more waterproof than others, some have a higher melting point than other, etc.
On top of all the above, they add more or less thickener to give the grease its NGLI number...the viscosity for grease..its grade.
You can have a grade from 0000 all the way to 3 (maybe higher?). The 'oughts are light and the 3 is quite firm.
The thick greases will 'channel'...a bearing will turn in them and create a channel as it drives through the thick grease. This is one you wouldn't want in your wheel bearings.
The manufacturers will help you decide what the grease should be used for. It is hard to go wrong if you read the label.
So, that's what grease is..oil in drag!
Stuart
