Key Takeaways
- The M12 grease gun delivers 8,000 PSI at 2.6 oz/min in a compact 14-inch, 7.2-pound design ideal for automotive, tractor, ATV, and trailer maintenance.
- The M18 provides 10,000 PSI with dual-speed operation (3.5 oz/min for stubborn fittings, 10 oz/min for rapid filling) and is suited for excavators, dozers, and fleet maintenance.
- Runtime varies significantly: the M12 dispenses up to 7 cartridges per charge, while the M18 dispenses up to 10 cartridges per charge, enabling extended maintenance sessions.
- The M18's 48-inch hose and lock-on trigger benefit high-volume users, while the M12's lighter weight and lower cost suit occasional or light-duty applications.
- GenuineTools offers both models at competitive prices with factory-sealed packaging and a 30-day money-back guarantee.
Core Differences Between M12 & M18 Grease Guns
The M12 grease gun has a more compact profile than its M18 counterpart. The M12 measures 14 inches long, while the M18 extends to 15 inches. The weight difference is noticeable but not as dramatic as you might expect: the M12 weighs approximately 7.2 pounds (bare tool), while the M18 comes in at around 7.6 pounds bare.
For professionals working in cramped engine compartments or reaching difficult angles, the M12's smaller footprint and lighter weight provide a meaningful advantage. However, the M18's slightly larger size accommodates its enhanced capabilities, which we'll explore further.
Pressure Output & Flow Rate Comparison
The M12 delivers a maximum pressure of 8,000 PSI, which effectively handles most automotive and light equipment maintenance tasks. The M18 steps up to an industry-leading 10,000 PSI maximum output, providing the additional force needed for heavy machinery and industrial applications.
The M18 also features dual-speed operation: a high-speed setting delivers up to 10 ounces per minute for rapid filling of larger bearings, while the low-speed setting provides 3.5 ounces per minute with maximum pressure for precision work and stubborn fittings.
The M12 operates at a single speed, delivering approximately 2.6 ounces per minute, which is adequate for most maintenance tasks but potentially limiting when working with larger equipment.
Battery Life & Cartridge Capacity
Battery performance is another significant differentiator between these models. The M12 operates on Milwaukee's 12V battery platform and can dispense up to 7 grease cartridges per charge.
The M18, powered by Milwaukee's more robust 18V battery system, delivers substantially longer runtime, dispensing up to 10 cartridges per charge. For professionals handling multiple greasing points or working extended shifts without access to charging, this runtime difference can dramatically impact workflow efficiency.
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Milwaukee® M12 Grease Gun Specifications
Milwaukee's M12 model features a 36-inch flexible hose and air bleeder valve for reliable priming without air pocket issues.
The M12 grease gun delivers impressive specifications for its size class. It operates at a maximum pressure of 8,000 PSI with a flow rate of approximately 2.6 ounces per minute. The 36-inch flexible hose provides reasonable reach for most applications, while the integrated shoulder strap makes transport between greasing points more convenient.
The unit accepts standard 14.5-oz grease cartridges and offers a bulk-loading option for those who prefer to use grease from bulk containers.
Design & Ergonomics
The M12’s lightweight construction delivers durability while keeping the weight manageable at 7.2 pounds. Its ergonomic grip and balanced in-line design reduce fatigue during extended use, making it particularly valuable for technicians handling multiple greasing points.
One of the M12's standout features is its air bleeder valve, which ensures reliable priming without the frustration of air pockets disrupting grease flow. The integrated LED fuel gauge helps monitor battery life, preventing unexpected interruptions mid-task. The tool also includes overload protection to help prevent damage during demanding applications.
Runtime & Performance
The M12 delivers up to 7 cartridges per charge, which is enough for most single-session maintenance tasks. Its 8,000 PSI pressure and 2.6 oz/min flow rate handle standard grease fittings on tractors, mowers, ATVs, and trailers without issue.
However, severely clogged or frozen fittings on older equipment may require more pressure than the M12 provides, and the single-speed flow rate means more time at each point when filling large bearings.
Best Applications for the M12
The M12 grease gun is suited for automotive maintenance, farm equipment, and general machinery servicing. Its compact design makes it easy to carry across job sites and maneuver in tight spaces where larger grease guns struggle. The tool also works well for routine maintenance on vehicles, trailers, and smaller construction equipment with multiple grease fittings.
Milwaukee® M18 Grease Gun Specifications
The M18 grease gun's 48-inch hose and 10,000 PSI output handle hard-to-reach fittings on excavators, dozers, and heavy equipment.
The Milwaukee® M18 grease gun delivers a maximum operating pressure of 10,000 PSI for stubborn or clogged fittings. The dual-speed design offers a low-speed setting at 3.5 oz/min for maximum pressure on difficult fittings, and a high-speed setting at 10 oz/min for rapid filling of large bearings.
The 48-inch flexible hose extends reach compared to the M12's 36-inch hose, and the tool dispenses up to 10 grease cartridges per charge.
Design & Ergonomics
The M18 features a preset grease counter dial that dispenses precise amounts to prevent over-lubrication. An on-board LED illuminates dark work areas, while the lock-on/lock-off trigger reduces hand fatigue during extended sessions.
The plunger rod includes markings to gauge remaining grease, and the air bleeder valve ensures reliable priming. At 7.6 pounds (bare tool), the stand-up design and shoulder strap make it easy to handle the tool all day.
Runtime & Performance
The M18's 10,000 PSI pressure handles virtually any greasing task, including frozen fittings and excavator track tensioning that defeat lower-powered guns. Like all grease guns, proper priming after cartridge changes prevents airlocks.
For users who maintain only small equipment, such as riding mowers or ATVs, the M18's additional size and cost may be unnecessary, as the M12 handles those applications capably.
Dual-Speed Operation
The M18's two-speed switch lets users select between max pressure (3.5 oz/min at 10,000 PSI) for stubborn or clogged fittings, and max flow (10 oz/min) for rapid filling of large bearings, fifth wheels, and high-capacity grease points.
The high-flow setting delivers nearly three times the output of the M12, reducing time spent on large-volume tasks like tensioning excavator tracks or packing wheel bearings. A simple toggle switches between modes without interrupting work.
Best Applications for the M18
The M18 excels in high-volume maintenance: excavators, dozers, loaders, large agricultural tractors, and semi-truck fleets. Its 10,000 PSI pressure clears clogged fittings that defeat lower-powered guns, while the 10 oz/min flow rate handles track tensioning and large bearings efficiently.
With up to 10 cartridges per charge, technicians can complete full maintenance sessions on multiple machines without swapping batteries.
Price Breakdown
The complete M18 kit includes the grease gun, battery, charger, and tool bag.
Milwaukee's M12 grease gun retails for around $199 as a bare tool. It’s currently discounted to $95.99 on GenuineTools. At $279, the M18 bare tool commands a higher price but is also discounted to $169.99. For buyers who need batteries and a charger, the M18 kit retails for $349 but is available for $219.99 on GenuineTools.
Milwaukee® Grease Gun M12 vs M18: Comparison Table
|
Feature |
M12 Grease Gun |
M18 Grease Gun |
|
Maximum Pressure |
8,000 PSI |
10,000 PSI |
|
Flow Rate |
2.6 oz/min (single speed) |
3.5 oz/min (low) / 10 oz/min (high) |
|
Hose Length |
36 inches |
48 inches |
|
Runtime |
Up to 7 cartridges |
Up to 10 cartridges |
|
Tool Length |
14" |
15" |
|
LED Light |
Battery fuel gauge |
Work light |
|
Lock-on/Lock-off Trigger |
No |
Yes |
|
Price at GenuineTools (bare tool) |
$95.99 |
$169.99 |
Choose Your Milwaukee® Grease Guns at GenuineTools
GenuineTools carries both Milwaukee® M12 and M18 grease guns at up to 60% off the Manufacturer's Suggested Retail Price (MSRP), far exceeding the 10–30% discounts offered by most competitors.
We ship every grease gun factory-sealed in the original packaging. Fast fulfillment from our U.S. warehouses means your M12 or M18 grease gun arrives quickly, keeping maintenance schedules on track.
Our customers consistently praise our competitive pricing and our excellent customer service.
Whether you're servicing a single tractor or managing a fleet of excavators, our experienced tool specialists help you match the right model to your application. Bulk purchasers benefit from volume pricing and dedicated support tailored to contractor and fleet maintenance operations.
All purchases include our 30-day money-back guarantee and full refunds for approved returns. From bare tools to complete kits with batteries and chargers, we stock the accessories needed to build a complete cordless lubrication system compatible with your existing Milwaukee® tool lineup.
Frequently Asked Questions (FAQs)
Can I use different grease types in Milwaukee® grease guns?
Yes, both the M12 and M18 Milwaukee® grease guns are compatible with most standard NLGI #1 and #2 greases. However, extremely thick greases (NLGI #3) may increase strain on the motor and reduce flow rates, particularly in the M12 model.
Lithium complex, calcium, and synthetic greases all work effectively, though you should always purge the system when switching between incompatible grease types.
How long does it take to charge the batteries for each model?
Using Milwaukee's multi-voltage charger, compact batteries (2.0Ah) reach full charge in approximately 30 minutes, while extended capacity batteries take around 60 minutes. Rapid and superchargers can reduce these times by up to 40%, though these chargers are typically sold separately from standard kits.
Can I convert from bulk fill to cartridge loading?
Both Milwaukee® models offer flexible loading options, including standard 14-oz cartridges, bulk loading from pails, and suction filling from bulk containers. Converting between these methods requires following the proper priming procedure detailed in the user manual to avoid air pockets that can cause inconsistent operation.
The bulk-loading capability is particularly valuable for high-volume users, who can save significantly on lubricant costs by purchasing grease in larger quantities rather than individual cartridges.
Where can I find the best deals on Milwaukee® M12 and M18 grease guns?
GenuineTools offers both Milwaukee® grease gun models at competitive prices, up to 60% off MSRP. Our team also provides guidance on selecting between the M12 and M18 based on your equipment and maintenance needs. Every item you purchase from us is backed by a 30-day satisfaction guarantee and responsive customer service reflected in our positive Trustpilot ratings.
*Note: Pricing and/or product availability mentioned in this post are subject to change. Please check the GenuineTools website for current pricing and stock information before making a purchase.