Grease Fitting

What Are Grease Fittings and Why Do They Matter?

Grease fittings — also commonly called Zerk fittings, grease nipples, or Alemite fittings — are small but essential metal components found throughout automotive, agricultural, marine, and industrial equipment. Their job is deceptively simple: they provide a pressure-sealed access point that allows a grease gun to inject lubricating grease directly into a bearing, joint, or pivot point. Without them, routine lubrication of critical moving parts would require disassembly, turning a quick maintenance task into a time-consuming teardown.

In the automotive world, grease fittings are most commonly found in suspension systems, steering linkages, universal joints, and chassis components — anywhere two metal parts rotate, pivot, or slide against each other under load. The ball-check valve built into each fitting serves a dual purpose: it opens under grease gun pressure to admit fresh lubricant, and it snaps shut to prevent contaminants like dirt and grit from migrating into the bearing. Regular use of grease fittings reduces friction and wear, extending the service life of components that would otherwise fail prematurely.

Types of Grease Fittings

Selecting the right grease fitting for your application goes beyond just grabbing the nearest Zerk. Several configurations exist to solve different access and environmental challenges:

• Straight (Standard) Fittings: The most common design, used wherever a grease gun can access the fitting head directly without obstruction.
• 45° and 90° Angled Fittings: Designed for tight quarters where a straight approach is impossible, angled fittings redirect the grease gun coupler to reach otherwise inaccessible lubrication points.
• Button-Head Fittings: Feature a wider, low-profile head that handles high-pressure lubrication without leaking — frequently seen on heavy equipment and construction machinery.
• Flush (Flat-Head) Fittings: Sit nearly flush with the surrounding housing to prevent snagging on guards or passing material, requiring a special flat-face coupler to seal properly.
• Drive-Type Fittings: Pressed or driven into pre-drilled holes rather than threaded, ideal for high-volume production line installations.

Thread Sizes and Materials

Matching the correct thread standard to your application is critical — using the wrong thread can result in stripped ports and failed seals. The two dominant thread standards in North America are 1/8" NPT (National Pipe Thread, a tapered thread used in heavy industrial applications) and 1/4"-28 SAE (a straight thread common in automotive and light-truck applications). Metric sizes such as M6, M8, and M10 are standard on international and import equipment. Material choice also matters: zinc-plated steel handles most automotive and general-purpose tasks, while stainless steel is preferred for marine or corrosive environments where standard steel fittings would rust shut.

Top Grease Fitting Brands

When it comes to dependable grease fittings, a handful of manufacturers have earned the trust of professional technicians and serious DIYers alike.

Lincoln Lube is widely regarded as the benchmark for lubrication fitting quality. Lincoln lube fittings are used by automobile, agricultural, truck, and construction equipment manufacturers by the millions every year, and their comprehensive lineup spans threaded, thread-forming, drive-type, stainless steel, pressure-relief, and button-head configurations — ensuring there is a Lincoln fitting for virtually every application.

Edelmann brings decades of fluid-system expertise to the grease fitting category, offering reliable fittings trusted by professional service shops working on passenger cars, trucks, and light commercial vehicles.

Alemite is one of the most historically significant names in lubrication hardware — the original Zerk fitting patent was assigned to the Alemite Manufacturing Corporation back in 1929, and the brand has been synonymous with precision lubrication fittings across aerospace, industrial OEM, and automotive service applications ever since.

Lumax rounds out the category with practical, value-oriented grease fittings and lubrication accessories that appeal to both independent shops and home mechanics looking for reliable performance at a competitive price point.

Titan Tools complements their tool-focused lineup with grease fitting assortments ideally suited for technicians who want a go-to solution for restocking their service bay with commonly used Zerk sizes and thread types.