How to Load a Grease Gun for the First Time

What you need before you start

Most hand-operated grease guns work the same way: a barrel holds the grease, a plunger rod and spring or piston push it forward, and a head with a lever pumps it out. Loading is mostly about getting grease into the barrel without trapping air.

Gather a few things first. Keep these within reach so you do not have to wander around with greasy hands:

• A grease gun and a fresh grease cartridge, or a tub of bulk grease
• Safety glasses and a pair of nitrile gloves
• A few clean rags or shop towels
• A grease that matches what the equipment calls for (check the owner's manual)

Choose how you will load it

There are three common ways to fill a gun. The right one depends on the gun and on what grease you have on hand. Cartridge loading is the easiest for a first-timer, because the grease is sealed in a tube and there is little mess.

Do not mix different grease types without checking the equipment manual, since some greases do not get along when blended.

Load a cartridge step by step

This is the method most people mean when they ask how to load a grease gun. Work over a rag or a drip tray, because a little grease will escape.

Always follow the instructions printed on your cartridge and in your gun's manual, since designs vary slightly.

• Unscrew the barrel from the head and set the head aside on a clean rag.
• Pull the plunger rod all the way back and lock it in place. Many guns have a small notch where you turn the rod handle to hold it.
• Remove the plastic cap and the foil seal from the open end of the cartridge. Leave the other end alone.
• Slide the cartridge into the barrel with the open end facing the head.
• Screw the head back on until it is snug, but do not force it.
• Unlock the plunger rod so the piston or spring can push against the back of the cartridge.

Loading a gun with a spring-loaded rod

A spring-loaded gun has a spring behind the piston that keeps steady pressure on the grease. When you pull the rod back, you compress that spring, and locking the rod holds it there while you insert the cartridge or fill the barrel.

The key moment is releasing the rod. Hold the gun pointed at a rag or the floor, keep your face away from the head and turn the rod handle to let it go. If the spring snaps forward fast, the grease may push out of the nozzle, which is normal during the first few moments.

If the rod will not lock, check that you pulled it fully back and rotated it into its notch. Never force it, because a bent rod makes the gun harder to load every time after.

Loading without a cartridge

If you do not have a cartridge, you can use bulk grease. A grease loader pump is the cleanest route, since it pushes grease through a fill fitting on the gun. Connect the loader to the fill fitting and follow the gun's manual for how many strokes to give it.

With no loader, a hand fill still works. Pull the rod back and lock it, then unscrew the head. Scoop grease into the barrel with a clean putty knife or spoon, pressing it down as you go so there are no hollow pockets. Fill to about an inch below the rim, wipe the threads clean and screw the head back on.

Hand filling leaves more air in the barrel than the other methods, so expect to spend extra time purging. Keep the grease tub covered between uses so dust and grit do not get inside.

Prime the gun and remove air

Air in the barrel makes a gun sputter and stop pushing grease, so priming matters even when the loading went smoothly. Point the nozzle at a rag and pump the lever slowly until a steady bead of grease comes out. This can take a good number of strokes on a fresh load.

If grease still will not come, loosen the head about a half turn while you hold the lever. Trapped air escapes around the threads, then you can tighten it again. Some guns also have a small bleeder valve on the head for this job.

Once you see a steady, bubble-free bead, wipe the nozzle and you are ready to attach the gun to a fitting.

Check the coupler before you use it

A gun that is loaded well can still leak at the fitting if the coupler is worn or the wrong size. The coupler is the part on the end of the hose or head that grips the Zerk fitting. Every coupler on our best grease gun for the money list uses a 1/8 in NPT thread, so confirm your gun uses the same size.

If you grease recessed fittings often, a longer coupler can help. In our listings, the LockNLube XL is 5.5 in long and is rated to 10,000 psi, while the standard LockNLube 1/8 in NPT model is 3.45 in long and weighs 4 oz. Both are locking couplers that include a rebuild kit. For a closer look at the options, see our best grease gun coupler comparison.

Match the pressure rating to your gun. The gun sets the pressure you actually use, and the coupler should be rated at or above it.

Safety notes

Grease guns build real pressure, so treat them with care. Wear safety glasses every time, since a split hose or popped coupler can spray grease.

Never point the nozzle at your hand, finger or any part of your body. Grease forced under the skin is a medical emergency even if the wound looks small, so get medical help right away if it happens. Do not use compressed air to push grease out of a manual gun, and never exceed the pressure rating printed on your gun or coupler.

Frequently asked questions

Why is my new grease gun not pumping?

Air is usually trapped in the barrel. Loosen the head slightly while pumping the lever, then tighten it once grease flows steadily.

Do I need to remove the cartridge foil?

Yes. Take off the cap and any foil seal from the open end, or the grease cannot leave the tube.

How do I know the gun is full enough?

A cartridge fills the barrel for you. With a bulk fill, leave about an inch below the rim so the head can seal.

Can I leave a partly used cartridge in the gun?

Yes, in most cases. Store the gun level in a clean, dry spot and wipe the nozzle so dust does not stick to it.

How often should I replace the coupler?

Replace it when it leaks, will not stay on a fitting or feels loose. A rebuildable coupler lets you swap the seal and jaws instead.