S-706 Lever Action Grease Gun

Frequently Asked Questions: Medium Duty Lever Action Grease Gun 8,000 PSI

What is a medium duty lever action grease gun used for?

A medium duty lever action grease gun at 8,000 PSI is for workshop service on automotive, agricultural, and light industrial equipment where 6,000 PSI standard guns occasionally stall on crusted fittings but full 12,000 PSI industrial guns are unnecessary overkill. The S-706 handles passenger vehicle chassis, agricultural tractors, light construction equipment, fleet trucks, and manufacturing maintenance. The 4-way loading (cartridge, bulk, suction, filler pump) adapts to different grease supply chains.

Is 8,000 PSI enough for a grease gun?

Yes, 8,000 PSI (550 bar) is sufficient for almost all automotive, agricultural, and general industrial grease fittings. The S-706 at 8,000 PSI forces grease through crusted zerk fittings that would defeat 6,000 PSI guns, while staying below the 10,000+ PSI range where operator technique and seal protection become bigger concerns. Any bearing lip seal can fail at 500 PSI, so stroke count discipline matters more than gun peak pressure. The 8,000 PSI rating is the practical sweet spot for mixed workshop service.

How many strokes does the S-706 need per chassis fitting?

The S-706 delivers 1 gram per stroke (1 oz. per 28 strokes). A typical chassis fitting needs 3-5 strokes (3-5 grams). A U-joint needs 5-8 strokes. A sealed wheel bearing via zerk needs 10-15 strokes. Always stop when fresh grease appears at the fitting seal. Over-pumping blows rubber boots and contaminates brake components. Match the stroke count to equipment service manual specifications where available. Count strokes rather than pumping by feel.

Can I use both cartridge and bulk grease in the same grease gun?

Yes, the S-706 supports both cartridge (14 oz. / 400 g) and bulk (15 oz. / 500 cc) loading as designed. The same gun accepts either method. Switch between them without modification. But if you switch between different grease types (different thickener chemistry), the gun must be fully flushed before the new grease goes in, because residual grease from the previous type will mix at the follower plate and can form hard deposits. Switching between NLGI grades of the same thickener (NLGI 1 and NLGI 2 lithium) is safe without flushing.

How do I load the S-706 with a filler pump?

To fill the S-706 from a filler pump. Connect the filler pump nozzle to the S-706 bulk filler port or press it against the bottom cap opening. Next, retract the S-706 plunger rod fully. Then, operate the filler pump to push grease into the S-706 barrel. After that, watch the plunger rod extend outward as the barrel fills. From there, stop when the plunger reaches full extension. Finally, loosen the manual bleeder plug on the head 1/4 turn during filling to release trapped air, then retighten. Filler pumps are faster and cleaner than dip-loading from an open pail, and are the standard workshop method for rapid reloading across multiple guns. Note: the S-706A V-Series has an automatic air bleeder valve that does this step without operator intervention.

Can I use a lever grease gun on excavator pins and bushings?

Yes, but excavator pins and bushings often require 10,000-12,000 PSI to force grease through heavily contaminated zerks. The S-706's 8,000 PSI handles excavator service on smaller machines (5-10 ton class) and equipment with regular greasing schedules. For larger excavators, heavy loaders, or equipment that has missed scheduled greasing and has badly crusted fittings, step up to the S-707 at 12,000 PSI. Use moly EP grease for excavator pins under heavy load, and inspect each pin for wear that needs mechanical service instead of just more grease.

Can I use a grease gun on a PTO shaft?

Yes, the S-706 works for greasing PTO (power take-off) shaft slip yokes, universal joints, and drive shaft bearings on agricultural tractors and implements. PTO shafts typically have 2-4 zerk fittings per shaft assembly. Use NLGI 2 moly-fortified grease or EP lithium for PTO applications due to the high shock loads. Grease the shaft with the PTO disengaged and the tractor off. For implement driveline shafts, extend and collapse the shaft through its full length while greasing to distribute grease along the inner splines.

Can I use the S-706 for wheel bearing packing?

For serviceable wheel bearings with external zerk fittings, yes. For repacking tapered roller bearings removed from the hub, hand-packing with fresh grease is the correct method, not gun-pumping. The S-706 works for truck and tractor hub zerks that accept grease injection. Pump slowly and stop when fresh grease appears at the rear hub seal. Over-pumping blows the seal and contaminates brakes. For Bearing Buddy style boat trailer spindle caps, pump one stroke at a time watching the spring-loaded piston move forward. Stop immediately when movement is visible.

Can I over-grease with a lever action grease gun?

Yes, over-greasing is one of the most common lubrication errors and causes more failures than under-greasing. Over-pumping forces excess grease past bearing seals, carrying dirt backward into the bearing, displacing the proper grease volume, and in some cases causing bearing cage damage from hydraulic pressure in sealed bearings. On the S-706, stop pumping immediately when fresh grease appears at the fitting seal or when the lever becomes noticeably harder to pump. Never force the lever. Count strokes per the equipment service manual specification.

Why is my lever grease gun losing pressure?

Pressure loss on the S-706 has four common causes: air lock in the barrel, worn plunger or head seals, loose head connection, or debris in the non-return valve. Diagnostic order. Loosen the head 1/4 turn while pumping until grease flows, then retighten (fixes air lock). Next, confirm the head is fully threaded tight after loading. Then, inspect the plunger rod seal and head o-rings for wear or damage. After that, disassemble and check the non-return valve for debris. Replacement seal kits are available as STAR spare parts. Never force the lever if it goes limp.

Can I use one grease for all applications?

No, different applications need different grease formulations. NLGI 2 multi-purpose lithium grease handles chassis joints and general bearings, but high-load points like ball joints and U-joints perform better with moly-fortified EP grease. Marine applications require water-resistant calcium sulfonate or aluminum complex grease. Food-grade equipment needs H1 or H2 certified grease. High-temperature applications above 80°C need polyurea or synthetic formulations. Using a single grease for everything leads to premature wear in specialized applications and cross-contamination when the gun switches to different equipment.

Can I rebuild my grease gun coupler?

Only specific coupler models are rebuildable. Standard budget 4-jaw push-on couplers are typically one-piece and must be replaced when worn. Premium hydraulic couplers and locking couplers from STAR are designed with serviceable internals and rebuild kits are available. To check: unscrew the coupler from the hose/extension. If internal parts (ball check, spring, seals) are accessible and listed in the STAR parts catalog, a rebuild kit exists. Symptoms of a worn coupler: grease leaks from the coupler body under pressure, coupler slips off zerk fittings during pumping, or grease flows too slowly. For rebuildable models: disassemble at the threaded joint, clean all parts with solvent, replace the worn ball check, spring, and gasket from the rebuild kit, lightly grease the o-rings with fresh grease, and reassemble. If the coupler body shows visible wear on the jaw faces, replace the whole coupler instead. Contact our team to confirm which coupler model you have before ordering a rebuild kit.

How should I store the S-706 between jobs and for long-term storage?

For daily/weekly storage: leave the S-706 loaded with grease, hang it vertically on a wall hook or rack with the head up and coupler down, bleeder plug tight. For long-term storage (over 30 days), three steps. Clean the coupler and hose of external grease to prevent dirt accumulation. Next, back off the lever so no residual pressure remains in the pumping chamber. Then, store in a dry location at 10-30°C with the bleeder plug tight to prevent grease oxidation. Avoid temperature extremes that separate grease oils from the soap base. When returning to use after extended storage, pump 3-5 strokes to waste before greasing actual fittings. The first strokes may contain oxidized grease or separated oil. Replacement parts (seal kits, follower springs, coupler rebuild kits, hoses) are available from STAR for any unit that needs servicing after long storage.

Can a grease gun hose burst and cause injury?

Yes. A 12 inch flexible hose operating at 8,000 PSI can burst if damaged, spraying grease and rubber fragments at dangerous velocity. Inspect the hose before every use: run fingers along the full length feeling for cracks, bulges, soft spots, or stiffness. Check crimp fittings at both ends for grease leaks that indicate crimp failure. Bulges mean internal braid has compromised. Replace the hose immediately. A 6,000 PSI grease injection injury is a surgical emergency. At 8,000 PSI the risk is higher. Always wear safety glasses and nitrile gloves, and never position your body in front of the hose or coupler during use. If injection occurs, go to emergency immediately and say it is a high-pressure grease injection injury.