How do I know how much grease to inject into a fitting?

Over-greasing is as damaging as under-greasing — excess pressure blows the grease seal and expels the grease that was protecting the bearing. For most automotive and light-equipment zerks: inject until you see fresh grease appear at the seal lip. Count the number of pumps and record it for future reference — a wheel bearing might take 3 pumps, a U-joint 1 pump. For fittings with a grease nipple that vents: pump until the vent releases. Do not force grease against resistance — if a zerk feels blocked, switch to a needle coupler and check the fitting before continuing.

What type of grease should I use?

NLGI grade 2 multipurpose lithium grease handles most automotive chassis, wheel bearing, and general purpose applications. For high-temperature applications (brake components, oven conveyor bearings): use a high-temp red grease rated for the operating temperature. For marine or wet environments: a water-resistant marine grease. For food-processing equipment: NSF H1-rated food-grade grease. Do not mix grease types — different base oils and thickeners are chemically incompatible and can break down lubrication properties. If switching grease types: purge the old grease fully before switching.

Why is grease coming out around the coupler instead of into the fitting?

Grease bypassing the coupler is a coupler-to-zerk mismatch. Cause 1: the zerk is a metric size (common on European vehicles) while the coupler is SAE — use a metric coupler. Cause 2: the zerk is damaged or cross-threaded — replace the zerk fitting with a new one (typically $0.50-2.00 each). Cause 3: the coupler ball check is worn — replace the coupler. Cause 4: insufficient engagement angle — reposition the coupler to engage squarely with the zerk.

Can I use a grease gun for all lubricants?

Grease guns are designed for grease (semi-solid lubricants) only. They are not suitable for oil injection or thin lubricants — the valve and check ball are designed for the viscosity and pressure of grease. For oil fittings on older equipment: use an oil can. For chain lube or penetrating oil: use the appropriate aerosol or drip applicator.

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How to Choose a Grease Gun: 4 Steps to Type, Pressure, and Coupler Fit

Last updated: 2026-09-04 · By NicheHive Editorial

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Choose the right grease gun for your application — pistol grip vs lever vs cordless, working pressure for zerks, cartridge vs bulk vs suction fill, and coupler types for standard and hard-to-reach fittings.

Grease gun selection comes down to two decisions: drive type (manual for occasional use, cordless for field use, pneumatic for fixed shops) and pressure rating (standard 3,000-7,000 PSI for most automotive work, up to 10,000 PSI for heavy equipment with packed zerks).

For coupler selection, see best grease gun couplers.

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