With so many zerk fittings and lubrication points on a truck and trailer it can be tempting to seek out a one-size-fits-all grease. In many cases, grease consolidation is not only acceptable, it's a good idea and a money-saver.
However, when it comes to chemical composition of greases, applying the wrong one in the wrong spot can be detrimental.
Greg Morris, Shell Lubricants' Americas product application specialist and team lead for greases, noted it's important to distinguish "moly" as molybdenum disulfide from organo-moly compounds. "When people talk about moly, they are generally referring to solid additives," he said, "not organo-moly, which is included in formulations as a friction modifier and not as a solid performance additive."
Grease color (red, tan, blue, etc.) has very little to do with performance with one exception: Black. Tom Gauerke, national fleet account manager for Chevron Lubricants, said the color black often indicates the presence of moly.
"Color is not really indicative of the performances of the grease," he said. "Grease can be red and have different performance characteristics – it could be a different thickness, it could have a different base oil. Typically black would indicate it has a solid lubricant in it such as moly, and we'll have moly greases that have 3% or 5%, and that moly is the solid lubricant that gives you a little bit additional lubrication."
Any component on an on-highway heavy-duty vehicle can use a moly grease, but ExxonMobil Commercial Vehicle Lubricants Applications Engineer Paul Cigala noted that U-joint and automatic slack adjuster manufacturers specify that molybdenum disulfide content must be 5% or less so that internal gearing in slack adjusters and needle bearings in U-joints don’t bind up.
Need a tutorial on the fundamentals of grease?Check out this week's 10-44 webisode in the video above.
