Short answer
Use the NLGI consistency grade, thickener type, and base-oil viscosity the bearing or gearbox manufacturer specifies. Confirm the new grease is compatible with the one already in service, and add the quantity and frequency the manufacturer lists. Too much grease can cause heat and seal damage.
NLGI grade and grease compatibility
NLGI grade describes consistency, from semi-fluid grades such as 00 used in some gearboxes to the common NLGI 2 used in many bearings. The thickener, such as lithium complex, calcium sulfonate, or polyurea, affects compatibility with other greases.
Greases with different thickeners may soften or harden when mixed. Purge the old grease or confirm compatibility before switching.
Check base-oil viscosity for speed and load
Slow, heavily loaded bearings generally need a higher base-oil viscosity than fast, lightly loaded ones. The bearing manufacturer’s guidance accounts for speed, load, and temperature.
Avoid over-greasing bearings
Relubrication quantity and interval depend on bearing size, speed, and environment. Over-greasing can raise temperature and push out seals; under-greasing leaves the bearing unprotected. Follow the manufacturer’s quantity and use a consistent grease gun output per stroke.
Label grease points by product so the right grease goes into each fitting.
Food-grade H1 grease in food and pharmaceutical areas
Where incidental food contact is possible, use a grease carrying the registration your facility’s food-safety plan requires, such as NSF H1, and confirm it on the current product data.
Frequently asked questions
Can I mix two different greases?
Avoid mixing greases with different thickeners unless compatibility is confirmed. Purge old grease when changing products.
Is NLGI 2 right for every bearing?
No. Use the grade the bearing or equipment manufacturer specifies for its speed, load, and temperature.
Does this guidance apply to robot joints?
No. Robot reducers and actuators use the lubricant the robot manufacturer specifies. See our robot reducer lubrication guide.
General maintenance information. Always follow your vehicle or equipment manufacturer’s requirements and the current product data. Questions? Email [email protected].
