Milwaukee M12 Vs M18 Grease Gun

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If you use certain types of machinery for your work or home projects, you know exactly how crucial a grease gun is.

Using a grease gun for lubrication doesn’t only make your tools and machine work efficiently, it also prevents rusting and premature wear and tear.

We dug deep into the different grease gun brands on the market today and found two models that some users rave about from the brand Milwaukee. You’ve probably heard about them if you’re a long time power tool user.

Regardless if you’re a professional handyman or a newbie on DIY home projects, this review will give you a detailed rundown of the Milwaukee M12 and M18 grease gun models, and hopefully help you pick one that matches your needs.

Let’s dive right in.


Milwaukee has been around the power tools industry for almost a century now. The brand was founded by AF Seibert Milwaukee and is well known for its power drills but its line of grease guns has also become a household name over the years.

Both the Milwaukee M18 and M12 grease guns are cordless, hence these models are quite popular with DIYers and amateurs. Despite this, both M18 and M12 are also being recommended by some professionals for heavy duty use.

The main difference between these two is their power source — M18 is powered by an 18V lithium battery, while the M12 has 12V of power.

You’ll know right away that M18 is a much bulkier, more professional looking grease gun compared to M12. The 2646-21CT M18 is almost 1.5x the size of the M12.

But does this mean that the bigger grease gun is better, too?

Here’s a quick and detailed comparison of the two:

SpecificationsMilwaukee 2646-21CT M18Milwaukee 2446-20 M12
Dimension20 inches long14 inches long
Weight9.3 lbs7.2 lbs
MaterialStainless steelMetal
Voltage18 volts12 volts
Output pressure10,000 PSI8,000 PSI
Run timeUp to 10 grease cartridges per chargeUp to 7 grease cartridges per charge
Flex hose length48 inches36 inches
Grease capacity16 oz14 oz

Milwaukee 2646-21CT M18


At first glance, the built quality of this grease gun model is undeniable. It looks and feels sturdy without being intimidating, and includes a few safety features for convenience.

The lock trigger is a commendable feature that allows the user to estimate the amount of grease in the barrel. If you’re new to using grease guns, this is a helpful design that could help you use the gun conveniently with just the right amount of lubrication.

It also has a LED light included, which is quite convenient when you’re working on dim areas or worse, when the power is out.


M18 features a 2-speed delivery, making it a very versatile tool that you can use for various machinery. Maximum pressure is about 10,000 PSI, which allows the gun to dispense enough grease even to heavy duty machines.

The lower speed option allows you to use this model when you’re working with smaller tools.

It has a maximum flow rate of 10 oz per minute, which is quite impressive considering the other brands of the same voltage.

Another factor that adds to its performance is the 48” flex hose that comes with it, allowing you to reach tight fittings and deeper spaces that need greasing.

Battery life

As with all cordless tools, battery life is a major consideration for most users. After all, it’s this convenient feature that sets them apart from their corded counterparts.

The Milwaukee 2646-21CT M18 is powered by a single 18-volt lithium-ion battery. A fully charged M18 can use up about 8-10 tubes of grease, which is a considerable amount especially for small machines for your home.

If you’ll be using more grease to lubricate bigger machines, you might want to consider a second battery. However, the battery does get fully charged quite fast, so another battery may only be needed for emergency purposes.


  • Powerful output pressure
  • Feels heavy duty
  • Includes a 48” flex hose
  • Can load up to 10 grease cartridges per charge
  • Lithium ion battery is included in the kit


  • Not designed for first time users and amateurs

Milwaukee 2446-20 M12


The body of the M12 is made of metal. For a smaller grease gun, the feel and build of the M12 is not flimsy or cheap. You can tell that despite its size, it’s designed to last and do a powerful job.

The sleek and lean design of this model is ideal for a cordless tool because it’s handy and lightweight, making it the tool to use for your quick DIY home projects.

One outstanding feature of the M12 is the LED fuel gauge that tells the user how much grease is left in the gun.


Compared to M18, this model is powered by a 12-volt lithium-ion battery. It is a significant difference power-wise, making the M12 the less favored model when it comes to performance.

It allows up to 8,000 PSI of maximum pressure, which actually is not as bad for a grease gun of this size. It is still a powerful tool that can use about 5-7 grease cartridges per charge. This should be enough for greasing bolts and common machines.

It’s also worth noting that it has a 14-oz grease capacity, which means that you might need to do 2-3 charging cycles to completely use the grease up.

More information on the battery life below.

Compared to M18’s 48” flex hose, the M12 grease gun includes a 36” hose. This might work for basic greasing but for more complex tools, you might need to get the longer hose.

Battery life

As mentioned above, a fully charged M12 grease gun can use up to 5-7 cartridges at once. With its 14-oz grease capacity, most users recommend getting a backup battery to eliminate unnecessary downtimes. Downtimes can happen with cordless grease guns if you’re working on projects that require heavy machine greasing for longer hours.

Users are torn with this fact. While some of them commend the portability and convenience of the M12, the 12-volt battery is not that impressive and they end up buying several battery replacements.


  • Portable and lightweight
  • Powerful at 8,000 PSI
  • Can load up to 7 grease cartridges at a time
  • Has a LED fuel gauge


  • Has a short battery life


After doing the research for these two powerful grease guns from Milwaukee, we can conclude that choosing between them will basically boil down to two things — power and portability.

The M18 is significantly a more powerful tool when it comes to design, performance, and battery life compared to the smaller M12 grease gun. The former is able to do greasing to complex structures and machines. The overall quality and feel of the grease gun is top notch as well. Unsurprisingly, it’s priced at a much higher point as well.

The latter, on the other hand, gets the point on portability. It’s lightweight and handy, making it ideal for first time users and smaller home projects.

Our recommendation is to go with the model that would meet your personal preferences for the project that you will be using it for.

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