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What is a Grease Gun?

Dale Marshall
Dale Marshall

A grease gun is a special tool used to inject lubricating grease, under pressure, into motors or other moving parts of machines. Grease guns, like the caulk guns they resemble, usually operate with a disposable grease cartridge, although some grease guns are filled manually. The different types of grease guns are characterized by the source of energy for creating the pressure that forces the grease out of the gun and into the motor being lubricated. Some popular types of grease guns are trigger-operated, lever-operated, pneumatic, and battery.

There are three main components of a grease gun — a metal cylinder that contains the grease itself; the propulsion control, which is either a trigger or a lever; and the grease delivery device, either a flexible hose or a rigid metal tube, both of which are fitted with a special nozzle called a "coupler." The grease cylinder is usually from 15 to 18 inches (38 – 46 cm) long, and the delivery device, whether rigid tube or flexible hose, can be anywhere from 12 to 36 inches (30.5 – 91.5 cm) long. An electric grease gun will include a regular power cord, and a pneumatic grease gun will have an attachment for an air hose. A type of grease gun that has gained in popularity is the cordless grease gun, which incorporates a battery pack that can be as large as the grease cylinder itself.

Many professional mechanics use air-powered grease guns.
Many professional mechanics use air-powered grease guns.

A grease gun is designed to handle grease that's often very thick, sometimes approaching the consistency of fudge. It must transmit that grease only to those parts of an engine that require such a heavy lubricant, without contaminating other parts of the engine and without permitting the grease itself to become contaminated. This is accomplished by the installation of a special fitting, variously called a grease fitting, a grease nipple, or a Zerk fitting. The fitting is installed in the motor's casing and has a spring-loaded protective cover that prevents contamination from entering and grease from escaping.

Correct operation of a grease gun requires both proper training of the operator and proper calibration of the tool itself. The operator needs to know the amount of grease required by the part being lubricated, and the amount of grease that will be discharged with every pump of the trigger or lever, because overlubrication can result in damage. The operator presses the nozzle of the grease delivery tube or hose against the Zerk fitting with enough pressure to open the spring-loaded cover and holds it in place while pumping the trigger or lever as many times as necessary to discharge to appropriate amount of grease. When done, the coupling is removed from the fitting, the cap snaps back in place, and no further attention is necessary.

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Discussion Comments


@SarahGen-- I had one that I had purchased from online too but it was a disappointment. Unless one is willing to pay more and get a nice, professional grease gun, the rest are not easy to use and require a lot of effort. They also waste a lot of grease. They can leak and there can be issues with the nozzle.

So a cheap one may be okay for people who need to use the grease gun once or twice a year. But it's definitely not a good idea to get a cheap one if it's going to be used regularly.


@donasmrs-- I think it also depends on the type of grease you're using. I use cartridges and I find that those are the easiest to load and use. If you're using a suction or grease pump, that requires a bit more skill and time in my opinion. So I suggest getting a grease gun that works with cartridges. Some of them actually allow you to use cartridge or one of the other types of grease and that's a good option too. If you find that you don't like using cartridges, you can always switch without having to get a new grease gun.

I also recommend reading reviews. Sometimes, a product is just not good quality and doesn't function well. If you want to take chances, read reviews of the product you're interested in to make sure that it's a good one. That's what I did. I got mine online and have been using it for three years now without any issues.


What is the best type of grease gun? I'm looking for something that's easy to use and it should be easy to load too. I had one a few years back that wasn't very good quality. It was very difficult to load so I only managed to use it a few times. I definitely don't want to fall into the same mistake again.


@Melonlity -- A lot of the time, there is grease packed in suspension components by the manufacturer and it never has to be replaced. It simply lubricates for as long as the vehicle is used and there is no need to replace it.

Meanwhile, I have heard of a few people installing their own grommets for lubricating suspension parts to deal with changing out grease.

At any rate, it is usually considered a good thing that suspensions don't have to have a grease gun taken to them as often. That means less maintenance and more money saved.


It used to be that automotive suspension components were almost always lubricated with heavy grease. That is not done so much anymore and some argue that more wear on cars has resulted. If that is true, I wonder why the ability to lube suspension components has been eliminated by a lot of manufacturers.

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    • Many professional mechanics use air-powered grease guns.
      By: uwimages
      Many professional mechanics use air-powered grease guns.