A question I hear a lot is ‘what is the best grease to use’.
While there are many specific greases on the market which you might require … there are also many general purpose or multipurpose greases that could ‘do the job’. So what is the best grease to use?
Maybe the better way to find the answer is knowing what the grease should be able to do for your application. Do you need high heat or pressure resistance? Should your grease be metal free or environmentally conscious? Do you need an extreme pressure grease?
You might think applying an inexpensive all-purpose grease is saving you money on that month’s P&L, but next month you might find you need to explain why there is a purchase for a replacement part or worse, a new machine to your owners.
Grease is there to prevent metal on metal abrasion in or on moving parts of your heavy machinery. If you are following the right preventative maintenance plan, you should be able to retain the life of your equipment and receive the best performance from it … but you need to be using the right grease. We should note oils and lubricating fluids are there for the same reason, but again they vary and should be chosen for the right reasons and application.
Check out your machines owner’s manual. If you don’t have it of it’s covered in layers of workshop dirt, keep in mind a few of the below pointers.
Is the machine exposed to a lot of water?
If you are protecting parts from wet environments it might be an idea to look at marine greases as they tend to have better ‘water washout’ capabilities, meaning they are tacky and will resist being washed away. Other abilities include protection against a salty environment. As rust is accelerated by salt, some have better additives for protection. They are generally perform under pressure too.
What parts are you greasing?
You’ll need to know the working temperatures of the part being greased. Choosing a grease that melts or has a low ‘dropping point’ is not what you want on a part that will experience regular high heat. Yes, you could keep reapplying, because it’s cheap, but the cost in reapplication and downtime might be outweighed by choosing a better quality (alternate base) grease. There is also the risk of speeding up wear. Choosing a calcium sulfonate grease will generally give you better heat resistant properties too.
Is that part under extreme pressure?
High stress, high load or high shock applications require ‘extreme pressure’ greases. Generally labelled EP. One type of grease that can withstand extreme pressure is molybdenum disulfide, or "moly” grease. It can work its way into the smallest of gaps to keep the two contacting surfaces apart. There are concerns when heat gets very high. A non-heavy metal choice would be calcium sulfonate which has similar properties that can protect against scaring too.
How hot is your environment?
If you’ve moved from a cold/freezing location to hotter one, your regular ‘go to grease’ will need to be different. Colder environments require less viscous grease as it will still set up in low temperatures, while the same grease would ‘melt’ in warmer environments. Really cold environments could make certain grease become hard and brittle. While some companies use their own reference numbers, the general system will use 0 or 1 for freezing/cold places and 2 or 3 for warmer/hotter locations.
What grease were you using previously?
So, you’re changing grease for one reason or another. Do you need to remove all the previous grease from the joint/bearing? If the ‘base’ is different it should be done. Best to use a degreaser and pressure wash. Mixing different greases can create issues. As an example, moving from lithium base to calcium sulfonate grease would require a total clean for best results.
Are you working in a environmentally sensitive area?
Environmental regulations are becoming stricter and for the right reasons. Contamination is a result of ‘any foreign body invading or polluting an area’. There are many greases on the market with heavy metals and 313 toxins in their makeup. Grease sloughing off could be contaminating water tables or sensitive environments. Understand if you need to be environmentally conscious for yourself or your company.
Find a grease that has the ability to allow the machine to work at it's best and enable you to complete your job in a timely fashion. The best grease for the job will not always be the most expensive, but will be the one which has a good cost benefit. If it is more expensive, it should save you costs elsewhere for example reduce reapplication and be better for life of the parts.
We cover this a little more in another topic 'What's the best thickener for my grease application?', but for general higher heat and pressure machines and jobs, most professionals turn to calcium sulfonate greases as it has a good balance of all requirements. The additional benefits are on the positive environmental aspects and this appears to becoming more important with ISO accreditation. Finally, be aware if you are changing the grease and the thickener (base soap) is different to the previous there may be the need to clean the parts thoroughly.