Best Grease Gun for Diesel Trucks (2026)

Compare the picks

21 October 2026

How we scored them

Each gun is scored on performance, build, value, safety and warranty, with the weights published on our How We Pick page. A stated warranty term earns warranty points; none of these states a safety certification.

Scores run from 9.2 to 9.8: each product’s point total is placed on that range, so more points always means a higher score.

What the listings tell you

We read the four listings end to end. Two are cordless electrics and two are manuals. The cordless pair states 12,000 PSI, though the Seesii also says 10,000 PSI in another bullet. Only the UTOOL states a warranty term. None states a pressure rating for the manuals, and none states a safety certification. The manual guns both list an air bleeder; the cordless pair does not mention one.

Where each gun fits

Think of these four as answers to different greasing routines. The UTOOL is the home-garage answer: a 4.13 lb pistol gun you operate with one hand, with a locking coupler that stays on the fitting and a bleed valve for the air pockets every manual gun gets. The 12-month warranty is the only one stated here, which suits a tool that will sit between oil changes.

The Seesii is the multi-machine answer: cordless, 3-speed, and the most complete kit here with two 2000 mAh batteries, a charger, four coupler and nozzle options, a 39.4-inch hose, an extension pipe, a shoulder strap and a case. The listing aims it at tractors, trucks, lawn mowers and boats, which is exactly the mixed fleet where one-button greasing pays off.

The DIYtoolifz is the stubborn-fitting answer: 12,000 PSI from a brushless motor with a 3-speed dial, built for heavy equipment. At 11.48 lb it is the heaviest pick here, so it suits a bench or cart more than a long day under trucks.

The OTC 2310 is the traditional answer: a lever gun with a die-cast head, an automatic air bleeder and a 24-inch hose, running on 14 oz cartridges. It has been listed since 2013, which tells you the design has survived a long time in the field.

Listing age is worth a glance too. The OTC has been listed since August 2013, the UTOOL since July 2023, the Seesii since May 2025, and the DIYtoolifz since October 2025. An old listing is not automatically better, but a design that has stayed on sale for over a decade has survived a lot of real-world use.

Buying guide: the best grease gun for diesel trucks

Manual or cordless

Count the fittings first. The UTOOL pistol grip works one-handed and needs no battery, which suits a truck or two in the home garage. The OTC lever gun is the traditional choice with a die-cast head and a 24-inch hose. For a fleet of trucks or farm equipment, the cordless Seesii and DIYtoolifz eliminate the pumping entirely; the Seesii even ships a shoulder strap. Cordless costs weight: 6.16 lb for the Seesii and 11.48 lb for the DIYtoolifz against 4.13 lb for the UTOOL and 5 lb for the OTC.

Pressure and clogged fittings

Pressure is what clears a stubborn fitting. The DIYtoolifz states 12,000 PSI from a brushless motor with a 3-speed dial stepping flow from 5 oz/min to 7 oz/min to 9 oz/min. The Seesii states 12,000 PSI in one bullet and 10,000 PSI in another, so treat its figure as approximate. The manuals state no pressure rating; they trade raw force for simplicity and the OTC’s larger pumping chamber. For diesel truck chassis fittings, any of these moves grease; the high-PSI cordless guns are for the fittings that fight back.

Couplers and hoses

The coupler is where cheap guns fail. The UTOOL lists a patented locking coupler with a flex hose and a push-button air bleed valve. The OTC lists a 3-jaw slim coupler with a 24-inch high-pressure hose and a 6-inch bent steel extension for tight spots. The Seesii kit includes a quick-release coupler, a standard coupler, a 90-degree adapter and a 39.4-inch flexible hose. A locking or quick-release coupler is worth more than raw PSI when you are under a truck.

Flow control

Speed control decides how much grease goes where. The DIYtoolifz lists a 3-speed dial with stated flow rates: 5 oz/min on low for precision work and delicate parts, 7 oz/min on medium for routine maintenance, and 9 oz/min on high for clogged fittings. The Seesii lists 3-speed control without flow rates. The manuals have no speeds at all; the UTOOL’s pistol grip meters by feel and the OTC’s lever by stroke. If you grease delicate fittings alongside chassis zerks, the dial with stated rates is the useful feature.

Kit contents

Compare what arrives in the box, not just the gun. The Seesii kit is the fullest: two 2000 mAh batteries, a charger, a quick-release coupler, a standard coupler, a sharp nozzle, a 90-degree coupler adapter, a 39.4-inch flexible hose, an extension pipe, a shoulder strap and a case. The UTOOL kit brings the gun, a locking coupler and a flex hose. The OTC brings the gun, a 6-inch bent steel extension, a 24-inch hose and a 3-jaw slim coupler. The DIYtoolifz listing gives no kit details beyond the gun itself, so check the box contents before you buy.

Warranty

Only the UTOOL states a warranty term: 12 months, accessories not included. The other three state none. A grease gun lives a hard life under trucks, so the stated warranty is a real tiebreaker here.

Garage Fit Check

• Storage: the UTOOL’s loop-and-lock storage keeps the hose tidy; the Seesii ships in a case.
• Batteries: the Seesii includes two 2000 mAh batteries and a charger; the DIYtoolifz listing gives no battery details.
• Cartridges: the OTC runs on 14 oz cartridges; check your grease stock matches.
• Weight in hand: from 4.13 lb for the UTOOL to 11.48 lb for the DIYtoolifz, per the listings.

Frequently Asked Questions

Manual or cordless grease gun for a diesel truck?

For one or two trucks, a manual gun like the UTOOL or OTC is enough and needs no charging. For a fleet or many fittings, the cordless Seesii or DIYtoolifz saves the pumping. Match the gun to the fitting count.

What PSI do I need?

The cordless pair states 12,000 PSI, which the listings aim at stubborn and clogged fittings. The manuals state no pressure figure. For routine chassis greasing, pressure matters less than a coupler that locks on.

What is the air bleed valve for?

Air pockets in the grease stop the gun from pumping. The UTOOL has a push-button bleed valve and the OTC an automatic air bleeder; both clear the air so grease flows again.

Do I need a locking coupler?

It helps a lot. The UTOOL’s locking coupler and the Seesii’s quick-release coupler stay on the fitting under pressure, where a plain coupler pops off. The OTC uses a 3-jaw slim coupler for tight spots.

Which grease gun has a warranty?

Only the UTOOL states one: 12 months, accessories not included. The Seesii, DIYtoolifz and OTC listings state no warranty term.

Can I use these on other equipment?

Yes. The Seesii listing names tractors, trucks, lawn mowers and boats, and the DIYtoolifz aims at heavy equipment. The manuals work anywhere a grease fitting exists. One cordless gun can cover the whole property.

Related: the best cordless grease gun, the best grease gun for automotive, the best grease gun for lifted trucks and lever vs pistol grease gun.