S-702 Mini Lever Action Grease Gun - 6 oz. / 150 cc

Frequently Asked Questions: Mini Lever Action Grease Gun 6 oz

What is the advantage of a 6 oz. mini grease gun over a standard 14 oz. gun?

A 6 oz. mini like the S-702 offers compact size, lower weight (0.75 kg vs 1.5+ kg), and easier access to tight spaces, while still delivering pro-grade 6,000 PSI pressure and 10-12 fittings of grease per load. Standard 14 oz. guns are too bulky for motorcycles, compact engine bays, and small agricultural implement fittings. The S-702's 44.45 mm barrel and 6 oz. capacity fit into mini grease gun holders in OEM toolkits bundled with rotavators and tractors, where a full-size gun would not fit.

Is a 6000 PSI mini grease gun better than a 3000 PSI one?

The S-702's 6,000 PSI is better for sealed bearings, crusted fittings, motorcycle linkage pivots, and any stubborn zerk where a 3,000 PSI gun fails. A 3,000 PSI gun (like the S-703) is better for general-purpose greasing where high pressure is not needed and cost matters more. The advantage of 6,000 PSI: grease forces through zerks even when the ball check valve is slightly stuck. The disadvantage: operators must be more disciplined to avoid blowing bearing seals by over-pumping.

How many grams of grease per pump does a lever grease gun deliver?

The S-702 delivers approximately 0.55 grams per pump (stroke), or 22 grams per 40 strokes (1 oz.). Output matches the other STAR mini guns (S-701, S-703, S-703E) for consistent dosing. Count strokes per the equipment service manual: typical chassis fittings need 3-5 strokes (1.5-3 grams); larger bearings need 10-15 strokes (5-8 grams). Some service manuals specify grease by volume. At 0.55 g/stroke and typical NLGI 2 density (~0.9 g/cc), one stroke is approximately 0.6 cc.

How do you suction fill a mini grease gun from a bucket?

To suction-load the S-702: (1) remove the coupler and any hose/extension, (2) submerge the head outlet into an open grease pail, (3) retract the plunger rod slowly while holding the gun vertically. The plunger retraction creates a vacuum that draws grease up through the head into the barrel. Suction fill is cleaner than bulk fill (no barrel disassembly), which is why it is preferred for quick refills between jobs and when switching grease types. Prime normally after loading.

How many pumps does it take to prime a lever action grease gun?

Most lever guns prime within 3-8 strokes after loading. On the S-702: pump the lever 3-5 times after bulk or suction loading, and grease should flow from the coupler. If grease has not appeared after 10 strokes, loosen the head slightly to release trapped air, then retighten and continue pumping. The S-702's extra-heavy follower spring applies constant pressure to the grease column, which keeps priming fast. Cold or hardened grease slows priming; let the gun warm to room temperature before use in winter.

Can I use a mini grease gun for tractor and mower maintenance?

Yes, the S-702 is well-suited for small and compact tractors, garden tractors, riding mowers, tillers, hay balers and small agricultural implements. The 6 oz. capacity covers a typical mower service session; the 6,000 PSI handles infrequent-service implement fittings that have dried out. We at STAR often bundle the S-702 as an OEM toolkit component with rotavators and agricultural implements. For full-size farm tractors with 20+ fittings per service, step up to the S-707 (14 oz.) or S-724 (24 oz.).

Can I use a mini grease gun on an ATV or UTV?

Yes, the S-702 works well for ATV and UTV maintenance. Common ATV grease points: A-arm bushings (front and rear), tie rod ends, ball joints, swingarm pivots, prop shaft U-joints, and drive shaft slip yokes. The S-702's 44.45 mm barrel reaches into the tight frame areas where ATVs hide their fittings. Use NLGI 2 multi-purpose grease for most points; moly-fortified grease is recommended for prop shaft U-joints on higher-stress UTVs used for work or plowing.

Can a high PSI grease gun damage bearing seals?

Yes. Pumping aggressively or continuing past the point of resistance can damage bearing seals even with a 6,000 PSI gun like the S-702. Most sealed bearing seals rate for 500 PSI or less at the seal face. The S-702 only reaches 6,000 PSI when the fitting is blocked; in normal service, grease flows at much lower pressure. Rules: stop pumping when fresh grease appears at the fitting or bearing seal; never force the lever if it feels hard; count strokes per the service manual rather than pumping by feel. If you notice leaking grease past the bearing seal during pumping, stop immediately: the seal is compromised and needs bearing replacement.

Why does my mini lever gun lose prime after suction filling?

Air lock happens when air enters the barrel during bulk or suction loading, preventing the pump from priming. To fix on the S-702: (1) loosen the head 1/4 turn while pumping the lever slowly until grease oozes out, then retighten; (2) if that fails, disassemble the barrel, manually pack grease against the follower plate to eliminate the air pocket, reassemble and re-prime; (3) prevent future air locks by retracting the plunger slowly during suction fill and tapping the gun on a bench after loading to settle the grease against the follower.

How do I inspect a grease gun hose for safety before use?

Before every use, run your fingers along the full length of the S-702's 10 inch flexible hose feeling for cracks, bulges, soft spots or stiffness. Check the crimp fittings at both ends for grease leaks, which indicate a failed crimp. Look for visible cracks in the rubber outer layer, especially near the crimps where the hose flexes most. A bulging section means the internal braid is compromised; replace the hose immediately. Damaged hoses can burst at 6,000 PSI, spraying grease and fragments. Replace the hose every 12-24 months in professional use, or immediately at any sign of damage.

Is it safe to combine lithium and calcium greases?

No, never mix incompatible grease thickeners without thorough cleaning between. Lithium, calcium, aluminum complex, polyurea and clay thickeners can react chemically and form hard deposits that clog the S-702 and degrade lubrication effectiveness. To switch safely: empty residual grease, disassemble via the demountable bottom cap, wipe and solvent-flush the interior, dry completely, lightly re-grease new o-rings with fresh grease, reassemble and load new grease. Workshops should keep separate labeled guns per grease type.

What is the proper grease gun maintenance schedule?

Clean the S-702 every 6 months for occasional use, every 2-3 months for weekly professional use, or whenever you switch grease types. Disassemble via the demountable bottom cap, wipe out old grease with a clean rag, flush with solvent if hardened, dry completely, lightly re-grease the plunger seal and o-rings, reassemble. Regular cleaning extends follower spring life and prevents priming issues. Mobile mechanics who use the gun daily should also inspect the hose crimp fittings during each cleaning.

Does cold weather affect grease gun storage and performance?

Yes. Cold temperatures stiffen grease and can crack o-rings; hot storage accelerates oil bleed. Store the S-702 horizontally at 5-35°C with the plunger rod disengaged. For cold-weather use: (1) store the gun indoors, not in an unheated shed; (2) switch to NLGI 1 grease (softer than NLGI 2) for operation below -10°C; (3) warm the gun to at least 10°C before use; (4) expect slower lever cycling until pumping friction warms the grease. Below -20°C, use synthetic or silicone-based low-temperature grease. Horizontal storage with plunger disengaged extends follower spring life and prevents grease separation.

What PPE do I need for grease gun work?

Always wear safety glasses and nitrile gloves, and never place your hand or body in front of the coupler tip or a pressurized hose. A 6,000 PSI grease injection injury is a medical emergency: grease injected under the skin can cause severe tissue damage, infection or amputation even from a tiny entry wound. If injection happens, go to an emergency room immediately and tell staff it is a high-pressure grease injection injury. Never bypass the coupler by pressing the gun tip directly against skin or a seal. Keep the gun pointed away from your body when priming.