There are some considerations that will help you decide which grease is best for your application and also save you some money along the way.
Grease in machinery has to be able to deal with friction, but it also has to overcome other contributing factors along the way.
Load, speed and temperature all can cause lubricants to fail to protect the machine properly, so you may not have a single good answer as to which product is best.
Lubricating products are generally either soap-based or petroleum-based, although one of my favorite stories from my college days involved the use of oleo margarine. Dr. W.F. Collins was a professor in the food science department at Virginia Tech and a staunch believer in the use of “100 percent all-dairy” products.
Shortly after his arrival in Blacksburg, he asked a technician in the dairy lab to mix him up some clear margarine. The technician, thinking that this must be some new research project, promptly whipped up a 55-gallon barrel of the clear grease for Dr. Collins and asked him where he needed it delivered.
“You made how much?” Dr. Collins exclaimed. “Heck, I just needed a little to grease my lawnmower! At my last post, I had the folks mix me up some black oleo, and I wanted the clear so you could tell where I had been!”
When asked what he should do with the excess, Dr. Collins instructed him, “Throw that stuff out. We use butter around here, son!”
Grease viscosity is greatest in the “moly” greases on the market. Moly stands for molybdenum sulfide, which is one of the best-known solid lubricants.
Originally available only to the aerospace and military, moly-based greases are widely available now for commercial and homeowner applications.
Moly greases work by filling surfaces that may have been roughened, contributing to an overall smoother surface finish and lowering friction.
This ability to fill in makes moly-based greases ideal for applications such as loader and backhoe pins, kingpins, ball joints, pivot pins and spherical frame pivot bearings. Its thicker formulation may also keep the grease from flowing as freely as needed on some applications.
On the other end of the spectrum are lithium-based greases. Lithium greases are soap-based, and as such, they are not as water-resistant as other forms of thicker, pasty grease.
The benefit to lithium grease is that it washes off more easily, and therefore, may be more desirable for visible applications, applications to high-speed parts (like roller chains), door hinges or around-the-house uses such as garage doors. Its thinner nature also allows it to be delivered in the form of a spray-on product, which can be very handy.
Just as in motor oils, there are now synthetic greases on the market that offer longer lubrication intervals as a means to offset the initial high price tag. In short, there is no clear-cut answer to which grease is best under all conditions.
To the contrary, research seems to suggest that basing decisions on conditions is how one should go about selecting the proper lubricant for the job. FG
Andy Overbay
Extension Specialist
Virginia Tech
