How Often To Grease Zerk Fittings: What You Need To Know Guide

How often do you need to grease your Zerk fittings? The short answer is: “it depends.” Zerk fittings are universally used on many types of machinery, and they all require different service intervals based on their need for lubrication. I have equipment that requires the fittings to be greased daily and others that can last over a year with 10,000 miles.

This post will discover the vast uses of zerk fittings and how often you should be greasing them.

Table of Contents

What Are Zerk Fittings?

Sealed Bearing

Before diving into Zerk fittings, let’s first discuss how they compare to sealed fittings. A sealed fitting has a set amount of grease placed inside a rubber boot that is permanently placed around a ball joint. This sealed joint requires no maintenance.

Sealed bearings are designed to keep out dirt and debris, leading to premature wear and tear on the component. They are also less likely to leak, making them a more reliable option in the long run.

The downside of the sealed joint is that it is not serviceable. So, if there is a crack or leak into the boot, that can cause dirt, dust, and water to enter the joint (causing failure). And the only option then is to replace the joint.

Zerk Fittings

Now, with a Zerk fitting, this is a serviceable ball joint that can receive new grease and be replaced with clean grease.

Zerk fittings are grease fittings used to lubricate bearings, gears, and other moving parts. Zerk fittings are inserted into a hole in the position to be lubricated, and then a grease gun is used to inject grease into the fitting. The grease is forced onto the part, providing lubrication.

Old grease comes out

This helps to ensure that the grease is distributed correctly and that no air pockets are formed. It also helps to keep the grease from leaking out of the bearing or other mechanisms.

The zerk fitting is a small hole (nipple) in the bearing that allows you to put grease in without having to take the bearing apart. This is an excellent feature for long-term use, as it keeps the grease inside the bearing and prevents it from drying out. It also helps keep dust and dirt out of the bearing, prolonging its life.

The fitting is named for its inventor, Merle Zerks, who developed the design in the early 1920s.

Where Are Zerk Fittings Used?

Zerk fittings are most commonly used on machines with difficulty reaching internal parts, such as motorcycles, cars, wheel bearings and trailers. Lubricating these parts can help improve performance and extend the machine’s life.

Zerk fitting on tractor control arm

Around my property, I have many things that use zerk fittings. My fifth wheel, tractor, car, and wheelbarrow all have zerk fittings. And, the thing is, they all have different times and amounts that the zerk fittings need to be greased.

How Do You Grease Zerk Fittings?

A grease gun is the most common way to grease a zerk fitting (or grease nipple). A grease gun is a tool that attaches to a can of lubricant or grease. The can is then inserted into the gun. The gun has a plunger on one end and a nozzle on the other.

To use the gun, you insert the nozzle into the hole on the zerk fitting and press down on the plunger to allow the grease to flow. This forces (grease pressure) the grease out of the can, through the nozzle, and into the fitting.

My grease gun with a flexible end

Since a zerk grease fitting joint is not sealed, the grease gun forces the old grease out of the grease fitting and is replaced by new grease. As the excess grease is pushed out of the fitting, you will want to wipe that with a rag or towel.

How Often To Grease Zerk Fitting?

As you learned above, a variety of pieces of equipment have zerk fittings. Below is a quick guide on how often to grease your zerk fittings. This guide is a quick reference, and your best bet is always to follow your manufacturer’s recommendation. They will consider the need for new grease on their part, i.e., ball joint, u joint, or wheel bearing.

A quick guide to how often to add fresh grease to your zerk fitting:

  • Tractor ball joints : Every day or 8 hours of use
  • Car or Truck sway bar or control arms : every 3,000 miles (figure to do at every oil change)


It is essential to grease zerk fittings often to keep them functioning properly. This will help to ensure that your equipment runs smoothly and lasts longer. Remember to always check the manufacturer’s recommendations for how often to grease zerk fittings, and be sure to use the correct type of grease.