A grease gun holds thick lubricant and pushes it into tight spaces where moving parts need protection

A grease gun is a handheld tool that stores grease and forces it through a nozzle into bearings, hinges, and other joints. The gun has a plunger you pump to build pressure, which pushes the grease out. Filling one takes about five minutes and requires only the grease cartridge and the gun itself — no special tools or skills.

The two most common types are cartridge guns (which hold a sealed tube of grease) and bulk-fill guns (which you load from a bucket or tub). This guide covers cartridge guns, which are simpler and more common for home and light shop use. The process is the same whether you are working on a lawn mower, a gate hinge, or a piece of farm equipment.

Key Takeaways

  • Cartridge grease guns hold a sealed tube that slides into the barrel, and you find it with a retaining cap at the back.
  • You must remove the plunger rod completely before inserting the cartridge, then screw it back in to push the grease out.
  • The nozzle (the tip that attaches to the grease point) screws onto the front of the gun and can be swapped for different sizes.
  • Once filled, the gun is ready to use when ready — no priming or warm-up needed.

Remove the plunger rod from the back of the gun

Open the rear of the gun by unscrewing the retaining cap (the metal ring at the very back). Turn it counterclockwise by hand — it should come loose without much force. Once the cap is off, you will see the plunger rod, which is a long metal shaft with a handle or knob at the end.

Pull the plunger rod straight out of the barrel. It will slide out easily once the cap is removed. Set it aside on a clean surface where you will not lose it. Do not force it — if it sticks, the cap may not be fully unscrewed yet.

Insert the grease cartridge into the barrel

Hold the gun with the open end (where the plunger came out) pointing upward. Take the grease cartridge — a sealed tube with a pointed metal tip on one end — and slide it into the barrel, pointed end first. The cartridge should slide in smoothly and sit flush with the back of the barrel.

If the cartridge does not slide in easily, check that the barrel is truly empty and that you are not trying to insert it at an angle. The cartridge is designed to fit snugly, so a little resistance is normal, but it should not require force.

Screw the retaining cap back on

Once the cartridge is seated, screw the retaining cap back onto the rear of the gun. Turn it clockwise by hand until it is snug. The cap holds the cartridge in place and also serves as the mount point for the plunger rod. Do not over-tighten — hand-tight is sufficient.

As you tighten the cap, you may feel slight resistance as the cap begins to compress the cartridge slightly. This is normal and helps create a seal. Stop when the cap feels firmly seated.

Reinsert and lock the plunger rod

Slide the plunger rod back into the barrel from the rear. It will slide in until it contacts the back of the cartridge. You may feel a small bump as the rod's tip touches the cartridge — this is correct. Push it in fully so the handle or knob sits flush with the back of the gun.

Some guns have a locking collar or clip that holds the rod in place once it is inserted. If yours does, slide it forward now to lock the rod. If there is no collar, the rod is held in place by friction and will not fall out during normal use.

Attach the nozzle to the front of the gun

Look at the front of the gun where the grease will come out. You will see a threaded opening. Screw the nozzle (the tapered metal tip) onto this opening by turning it clockwise. The nozzle should be hand-tight — do not use a wrench.

Grease guns come with one or two standard nozzles, but you can buy different sizes if needed. The nozzle screws off and on easily, so you can swap it to match the size of the grease point you are working on. A smaller nozzle fits into tight spaces; a larger one is faster for bigger openings.

Pump the plunger to prime the gun

Before you use the gun on your equipment, pump the plunger handle several times to push air out of the barrel and fill the nozzle with grease. You will feel the plunger get harder to push as pressure builds. Pump until grease appears at the tip of the nozzle — usually three to five pumps.

This step ensures that the first shot of grease goes into the bearing or joint, not into the nozzle. Once grease appears at the tip, the gun is ready to use. You do not need to do this again unless you have removed the cartridge and refilled.

Frequently Asked Questions

Can I refill a cartridge or do I have to throw it away?

Cartridges are sealed and designed to be thrown away once empty. They cannot be refilled at home. Some shops and service stations will refill them for a small fee, but most people straightforward replace them with new ones. Bulk-fill guns are an option if you use grease frequently and want to avoid the cost of cartridges.

What if grease leaks from the back of the gun?

Leaking usually means the retaining cap is not tight enough or the cartridge is not seated properly. Remove the plunger rod, check that the cartridge is pushed all the way in, and tighten the cap firmly. If it still leaks, the cartridge may be damaged — try a new one.

How hard should I pump the plunger?

Pump with steady, even pressure — do not jerk or force it. You should feel resistance build as the pressure increases, but the plunger should never be impossible to move. If it becomes very hard to pump, you may have air trapped in the barrel or the cartridge may be empty.

Do I need to clean the gun between uses?

No. Grease guns do not need cleaning between uses. If you change cartridges, wipe the nozzle with a rag to remove old grease, but the inside of the barrel will stay clean because the cartridge is sealed. If the gun sits unused for months, a light wipe of the exterior is enough.

Can I use any brand of grease cartridge?

Yes. Cartridges are standardized and fit any cartridge gun. The main difference is the type of grease inside — lithium, calcium, synthetic, or specialty blends. Choose the type your equipment manual recommends, but the cartridge itself will fit any standard gun.