Polyurea grease and lithium grease differ in five technically measurable ways: thickener chemistry, dropping point (260°C vs 180-200°C industry-typical for lithium soap), water washout resistance, service life in sealed bearings, and compatibility. This guide compares both as a manufacturer that produces each type, with a 5-year total cost of ownership model and a decision matrix by application.
All performance numbers cite ASTM and DIN test methods, and all ZTSH product specifications are taken directly from our published Technical Data Sheets.
What is the main difference between polyurea and lithium grease?
The main difference is the thickener. Polyurea grease uses a non-soap polyurea polymer — formed by reacting amines with diisocyanates in base oil. Lithium grease uses a metallic soap — typically lithium 12-hydroxystearate. This single chemistry difference cascades into every performance trait that follows.
Thickener structure: polyurea (non-soap) vs lithium soap
Polyurea thickener is a long-chain organic polymer with urea linkages. It is chemically inert at typical bearing operating temperatures and does not melt — it softens gradually toward its dropping point. Lithium soap, by contrast, is a crystalline metallic soap with a defined melting transition; once that transition begins, the grease structure collapses.
Why thickener type determines performance
Performance properties that depend directly on thickener type include: dropping point, water washout resistance, oxidation life, and compatibility with other greases. We will walk through each of these comparisons below.
Learn more in the industrial lubricating grease guide.
Dropping Point Comparison — 260°C vs 180-200°C
ZTSH Polyurea Grease has a confirmed dropping point of 260°C (per GB/T3498, equivalent to ASTM D2265). Simple lithium soap grease drops at 180-200°C industry-typical. This 60-80°C difference is the most cited performance gap between the two — and it has direct implications for which grease can safely run at elevated temperatures.
How dropping point is measured (ASTM D2265)
ASTM D2265 places a small grease sample in a brass test cup with a tapered bottom hole. The assembly is heated in an oil bath at a controlled rate. The dropping point is the temperature at which the first drop of liquid falls through the hole — indicating that the thickener structure can no longer retain the base oil.
Operating temperature vs dropping point — the practical limit
A common rule of thumb is that continuous operating temperature should sit well below the dropping point. ZTSH Polyurea Grease has a verified operating range of -20°C to 220°C, with the 260°C dropping point providing margin above the upper operating limit. The wider operating range than typical polyurea formulations is why this grease serves both standard electric-motor applications and demanding high-temperature roles.
| Grease Type | Dropping Point | Continuous Operating Temp |
|---|---|---|
| Simple lithium soap | 180-200°C (industry-typical) | up to 130°C |
| Lithium complex (ZTSH EP) | 270-280°C | -30 to 220°C |
| Polyurea (ZTSH) | 260°C | -20 to 220°C |
| Bentonite (industry-typical) | None (clay does not melt) | up to 600°C (Ultra-high formulations) |
Source: ZTSH Product Catalog (verified 2026); industry-typical values from NLGI Lubricating Grease Guide.
Water Resistance — Which Survives Wet Environments?
Polyurea grease shows under 2% water washout in ASTM D1264 testing at 80°C, while simple lithium grease loses 5-10% under the same conditions. For pumps, outdoor equipment, marine-adjacent machinery, and any bearings exposed to wash-down or rain, polyurea retains its protective film significantly longer.
ASTM D1264 water washout test
ASTM D1264 packs a bearing with grease, runs it at 600 rpm, and sprays water at 80°C onto the test housing for one hour. The grease loss is weighed and reported as a percentage. Lower is better. The test was originally developed for automotive wheel bearings exposed to rain.
Salt spray resistance — ASTM B117
For marine and coastal applications, ASTM B117 (salt fog cabinet test) is the relevant benchmark. Polyurea grease shows good salt resistance. The ZTSH Polyurea Grease specifically lists “excellent water resistance” as a characteristic in its product catalog, with confirmed corrosion resistance per GB/T7326 (T2 copper test, 100°C/30h: no green or black change).
Service Life and Re-greasing Intervals
In sealed bearings, polyurea grease commonly delivers 2-3× the service life of simple lithium grease. A well-formulated polyurea can sustain 10,000+ operating hours in a sealed electric motor bearing — often the lifetime of the bearing itself (“sealed-for-life”). Lithium grease in the same role typically requires re-greasing every 3,000-5,000 hours.
Why polyurea lasts longer (oxidation stability)
Service life of any grease is governed primarily by base oil oxidation. Polyurea thickener does not catalyze oxidation reactions, while metallic soap thickeners (especially copper-contaminated lithium) can accelerate them. Polyurea also resists the mechanical breakdown that thins lithium grease under repeated bearing rotation.
ZTSH Polyurea Grease lists “stable structure with no coking under high temperature” as a key characteristic, which is the practical consequence of polyurea’s oxidation stability.
Sealed-for-life vs re-greaseable applications
- Sealed-for-life: the bearing is greased once at the factory and never re-greased. Polyurea is the dominant choice — service life must equal bearing life.
- Re-greaseable: the equipment has grease fittings and a maintenance schedule. Lithium complex is cost-effective here because regular re-greasing offsets shorter individual life.
because regular re-greasing offsets shorter individual life.
Real automotive application: ZTSH’s published customer list includes CHERY Auto, where polyurea-grade greases are used in EV traction motor bearings requiring long-life sealed service. For broader customer reference, see the ZTSH OIL company profile.
Applications — When to Choose Polyurea vs Lithium
Choose polyurea when: the application is sealed-for-life, runs hot, runs wet, or has high downtime cost. Choose lithium when: the application is re-greaseable, runs moderate temperature, requires multi-purpose flexibility, or is cost-sensitive.
5 best polyurea applications
- Sealed electric motor bearings (industrial, automotive, EV)
- High-temperature pumps and fans (up to 220°C with ZTSH Polyurea)
- Outdoor or wet-environment bearings
- High-speed precision bearings (small machine tools)
- Centralized lubrication systems for premium equipment
5 best lithium grease applications
- Multi-purpose factory maintenance
- Automotive chassis lubrication
- Conveyor bearings (moderate temperature)
- Construction equipment pivots (ZTSH supplies HELI Forklift, KOBELCO, HITACHI in this segment)
- Agricultural machinery
| Application | Recommendation | Why |
|---|---|---|
| Sealed electric motor | Polyurea (ZTSH Polyurea Grease 2#) | Long life, no re-greasing access |
| Multi-purpose plant maintenance | Lithium complex (ZTSH EP Lithium Complex) | Cost-effective, broad compatibility |
| Steel mill hot bearings (>200°C) | Bentonite or Ultra-high Temp Grease | Beyond polyurea operating range |
| Marine deck winch | Polyurea (closest match in catalog) | Water resistance + temperature capability |
Compatibility Warning — Can You Mix Polyurea and Lithium?
No. Polyurea and lithium grease are chemically incompatible. Mixing the two causes thickener structure breakdown, resulting in hardening, softening, or oil bleed. Bearing failure can occur in days. Always purge fully when switching between these types.
Why mixing fails (chemical incompatibility)
The polyurea polymer and lithium soap have incompatible surface chemistries. When mixed, the soap structure begins to disperse into the polyurea matrix, but neither network is stable. The result is unpredictable consistency change — sometimes the mixed grease hardens enough to block grease lines; sometimes it softens enough to leak from seals.
Correct purging procedure (3-step method)
- Remove old grease mechanically. Disassemble accessible bearings; wipe out old grease with a clean rag. For sealed bearings without disassembly access, flush is acceptable but less reliable.
- Flush with new grease and run briefly. Pump in the new grease until purged grease exits clean. Run equipment for 10-15 minutes at low load, then check for color change.
- Re-pack with new grease. Fill bearing to 30-50% of free space (over-packing causes overheating). Document the change for traceability.
For all thickener-pair compatibility, see our full grease compatibility chart.
Cost Comparison — Total Cost of Ownership
Polyurea costs 1.5-2× more per kilogram than lithium grease, but TCO over 5 years is often lower for critical sealed applications. The factors are extended service life (2-3×), eliminated re-greasing labor, and reduced downtime risk.
Initial cost: polyurea vs lithium per kg
Wholesale industrial pricing varies by region and volume, but the typical premium for polyurea over lithium soap is 50-100%. Lithium complex sits between the two. The premium reflects polyurea’s more complex chemistry and tighter manufacturing controls.
TCO model: re-greasing labor + downtime + grease cost
For a sealed electric motor application running 8,000 hours/year:
| Cost Element | Lithium Grease (re-greased every 4,000 h) | Polyurea Grease (sealed-for-life, 10,000+ h) |
|---|---|---|
| Grease cost over 5 years | 1.0× baseline | ~1.8× baseline |
| Re-greasing labor (10 events × 1 hour) | 10 labor-hours | 0 labor-hours |
| Downtime per re-greasing event | ~30 min × 10 = 5 hours | 0 hours |
| Risk of contamination during re-greasing | Moderate | Eliminated |
| 5-year TCO | Higher than grease cost alone suggests | Lower for critical sealed bearings |
For re-greaseable, low-downtime-cost machinery, lithium remains the right answer. For sealed, high-downtime-cost machinery, polyurea wins on TCO despite higher purchase price.
ZTSH Polyurea Grease Specifications
| Property | ZTSH Polyurea Grease | Test Method |
|---|---|---|
| Thickener | Polyurea (non-soap polymer) | — |
| NLGI grade | 2# | ASTM D217 / GB/T269 |
| Appearance | Smooth even yellow ointment | Visual |
| Worked penetration | 265-295 (0.1mm, GB/T269) | ASTM D217 / GB/T269 |
| Dropping point | ≥260°C | GB/T3498 (≈ASTM D2265) |
| Operating temperature | -20°C to 220°C | — |
| Water loss (38°C, 1h) | ≤5% | SH/T0109 |
| Copper corrosion (T2, 100°C, 30h) | No green or black change | GB/T7326 (B method) |
| Extended working penetration change | ≤20 | GB/T269 |
Packaging available: 320g, 400g, 500g, 1kg, 2kg, 5kg, 12kg, 15kg, 170kg, 180kg.
Source: ZTSH OIL Product Catalog 2026, verified specifications.
To request the current Technical Data Sheet, samples, or pricing for your application, visit the ZTSH Polyurea Grease product page or contact our technical team.
Frequently Asked Questions
Can I mix polyurea and lithium grease?
No. They are chemically incompatible. Mixing causes thickener structure to break down, leading to hardening, softening, or oil separation. Always purge old grease completely before switching types.
Is polyurea grease worth the higher cost?
For sealed-for-life bearings, high-temperature applications (>150°C continuous), and equipment with high downtime cost, yes. For multi-purpose low-criticality use, lithium grease offers better cost-effectiveness.
What is the maximum operating temperature for polyurea grease?
ZTSH Polyurea Grease has a verified operating range of -20°C to 220°C, with dropping point ≥260°C providing thermal margin. This is wider than many industry-typical polyurea greases, which are sometimes rated only to 180°C continuous.
Why is polyurea grease used in electric motors?
Polyurea provides excellent oxidation stability, long service life, and stays in place during high-speed bearing operation. It is the industry standard for sealed-for-life electric motor bearings.
How do I switch from lithium to polyurea grease?
Step 1: Remove all old grease mechanically. Step 2: Flush with new grease and run briefly. Step 3: Re-pack with polyurea grease to 30-50% bearing fill. Never mix the two.
Is polyurea grease food grade?
Standard polyurea grease is not food grade. NSF H1 certified food-grade greases exist for food machinery and require separate certification. ZTSH OIL’s current catalog focuses on industrial and automotive applications; for food machinery applications, contact our technical team for application-specific consultation.
Conclusion
In summary, choosing between polyurea grease and lithium grease depends on operating temperature, environment, service-life requirements, and total cost of ownership rather than purchase price alone.
Three key takeaways:
- Match thickener chemistry to the application — there is no universally “best” grease.
- Cite test methods (ASTM / DIN / GB / NLGI) when specifying performance, not marketing terms.
- For critical or sealed bearings, calculate TCO over 5 years, not unit price.
For ZTSH product specifications and to request samples, visit the polyurea grease product page, browse the full lubricating grease range, or contact the engineering team.
Article by Dr. Wang Cuifeng, Director of Technical Affairs, ZTSH OIL (Anhui Zhongtian Petrochemical Co., Ltd.) — Published: 2026-05-27. Last reviewed: 2026-05-27.
Author: Dr. Wang Cuifeng, Director of Technical Affairs, ZTSH OIL Published: 2026-05-27 · Last updated: 2026-05-27 · Reading time: ~10 min