Lubricating Bearings for Electric Motors

How to get it right, avoid premature failure, and extend motor life.

Proper Bearing Lubrication Prevents Premature Motor Failure

When bearings fail, motors stop. And when motors stop, so does production. For many facilities, the root cause of bearing failure often comes down to one simple issue: improper lubrication.

Whether it’s too much, too little, or the wrong type of grease, poor lubrication practices can quietly shorten the life of your motor — long before any obvious signs of trouble appear. In this article, we break down the right way to lubricate electric motor bearings, based on trusted standards from EASA (Electrical Apparatus Service Association) and our field-tested experience.

Why Is Proper Bearing Lubrication Important?

Improper lubrication causes more damage than most people realize. Here’s what we see most often:

• Overgreasing: Excess grease can’t escape and builds up heat inside the bearing. This liquefies petroleum-based grease, reduces its ability to lubricate, and ultimately causes premature failure.

• Undergreasing: Not enough grease leads to metal-on-metal contact, which creates friction and scoring on the bearing surfaces.

• Inconsistent schedules: Skipping grease intervals or guessing based on feel leads to dry spots or clogged ports.

• Wrong grease types: Not all lubricants are compatible. Mixing greases with different chemical bases can cause them to separate or degrade faster.

"If you don’t have a procedure for how much grease and how often, you could be overlubricating your bearings and leading to premature failure.” – Jeff Martin, VP Shop Operations at Independent Electric

How Often Should I Lubricate Electric Motor Bearings?

The right interval depends on the motor’s:

• RPM

• Bearing size

• Operating hours

• Ambient temperature and environment

EASA provides detailed recommendations based on these factors. For example, a motor running at 1800 RPM in a clean, temperate environment may only need regreasing every 3–6 months, while high-speed or high-heat applications could require attention every few weeks.

Environmental Factors That Reduce Grease Life:

• Dirt or moisture exposure

• Higher ambient temperatures

• Vibration or heavy load cycling

• Vertical mounting positions

How Much Grease Should I Use on Electric Motor Bearings?

Too much grease is just as harmful as too little. Each motor requires a specific volume based on bearing dimensions.

General Rules of Thumb:

• Use calculated grease volumes — never just fill until it feels “full.”

• Remove the drain plug or use a relief fitting if available to avoid pressure buildup.

• Grease while the motor is running (when safe) to ensure even distribution across the bearing surfaces.

How Do I Choose the Right Lubricant for Electric Motor Bearings?

Using the wrong type of lubricant (or mixing different ones) leads to chemical separation and early breakdown. Here’s what to keep in mind:

• Always match the grease to the manufacturer’s specification for the motor or bearing

• Avoid combining different base oils (e.g., lithium and polyurea-based greases), unless specifically marked as compatible

• For high-temperature applications, synthetic greases may offer better stability and longer life than petroleum-based options

Best Practices for Regreasing Electric Motor Bearings

To make lubrication a dependable part of your motor maintenance plan:

• Establish a consistent greasing schedule tailored to motor conditions, OEM recommendations, and EASA guidelines

• Wipe grease fittings before and after each application to prevent contamination.

• Use temperature readings (infrared gun or thermometer) to catch early signs of overlubrication or underperformance

• Log grease volumes and dates in a service record — documentation helps identify trends before issues escalate

How Independent Electric Supports Your Motor Health

One way that our team helps our customers go beyond reactive maintenance is by incorporating better lubrication habits into their shop routines. Our team provides:

• Guidance on regreasing intervals and volumes tailored to your application

• Help evaluating and standardizing grease types used across your facility

• On-site training for proper lubrication procedures

• Full inspections during scheduled maintenance to assess bearing condition and identify early warning signs

We also apply insights from vibration analysis and thermal trends to confirm whether lubrication practices are working as intended or if they need to be adjusted based on the operating conditions of the motor.

A Smarter Way to Lubricate

A few extra minutes of precision when it comes to bearing lubrication can add years to your motor’s lifespan and save thousands in rebuild or replacement costs.

If you’re ready to standardize your lubrication approach, or you’re unsure if your current schedule is doing more harm than good, we can help.

Let’s talk about a preventative maintenance plan that keeps your motors running stronger, longer!