1.The differences in core components determine the upper limit of basic performance.

Composite lithium-based grease belongs to soap-based lubricating grease. It uses lithium soap of fatty acids and lithium salts of low molecular weight as the composite thickener. The structure contains lithium ions of metals and is usually combined with mineral oil or semi-synthetic base oils. It has a mature structure and stable process, and is currently a highly versatile high-temperature lubricating grease in industrial applications. 

The composite polyurea grease is a non-soap-based lubricant. It is thickened by a composite organic urea compound and the entire system does not contain metal ions. It belongs to a pure organic polymer structure. To take advantage of its high-temperature performance, it is usually combined with synthetic base oils such as PAO and esters. It is inherently a high-end route designed for harsh working conditions. 

The fundamental differences in composition directly determine the significant disparities in terms of high-temperature resistance, antioxidant properties, and lifespan between the two.

2.High-temperature performance comparison: Polyurea resin has a very obvious advantage.

Under high-temperature conditions, grease is most vulnerable to three issues: low drip point, rapid oxidation, and severe loss. Among these aspects, the composite polyurea grease is fully superior. 

In terms of droplet temperature and operating temperature, the droplet temperature of the composite lithium-based grease is above 260℃. The long-term operating temperature is generally 160℃, and it can reach up to 180℃ for short-term use, which is sufficient for routine high-temperature applications. 

The droplet melting points of the composite polyurea resin are generally above 280℃, and the high-end products can reach over 300℃. The long-term operating temperature can be stabilized at 200℃. Under light load conditions, it can even work continuously at 220℃, making it more suitable for ultra-high temperature scenarios. 

In terms of thermal oxidation stability, the composite lithium-based grease contains metal ions. At high temperatures, it will catalyze the oxidation of the base oil, easily resulting in the formation of sludge and a decrease in viscosity and hardness. The lifespan at 160℃ is approximately 1000 hours. 

The composite polyurea resin contains no metal ions and does not catalyze oxidation. Its structure is more stable. Under the same 160℃ condition, its service life can reach over 2000 hours, almost doubling the original lifespan. 

In terms of high-temperature loss resistance, the composite lithium-based grease is prone to damage to its soap fiber structure when exposed to continuous high temperatures, resulting in softening and loss. 

The composite polyurea grease relies on the hydrogen bond interaction between its molecular chains. Even at high temperatures, its structure remains stable, and the loss amount is much lower than that of the composite lithium-based grease. This provides more reliable long-term protection.

3.Actual application differences: Lifespan, environment, and cost are all clearly presented.

In the bearing life test, under the high-temperature condition of 180℃, the bearing life of the composite polyurea grease can reach 2 to 3 times that of the composite lithium-based grease. The lubrication film strength is higher and the wear is less at high speed and high temperature. 

In terms of water resistance and anti-pollution performance, the composite lithium-based grease performs reasonably well in resisting water seepage. However, its performance deteriorates significantly in high-temperature, high-humidity and steam environments. 

The composite polyurea resin has superior water resistance and chemical medium resistance. It remains stable even in humid, steamy and mildly corrosive environments, and is applicable in a wider range of scenarios. 

In terms of cost and versatility, the composite lithium-based grease offers high cost-effectiveness and strong versatility, making it suitable for most conventional high-temperature equipment. 

The cost of the composite polyurea grease is usually 2 to 4 times that of the composite lithium-based grease. Its application is limited to extremely harsh working conditions such as high temperatures, high speeds, and long service life. It is not recommended for use in ordinary low-temperature and low-speed scenarios.

4.Practical Selection Suggestions

Equipment temperature ≤ 160℃, mild working conditions, seeking cost-effectiveness: Preferentially choose composite lithium-based grease. 

When the equipment temperature is ≥ 160℃, if it is subjected to long-term high temperature/high speed/high load conditions and requires a long service life: Use the composite polyurea grease directly. 

Often, it's not the case that the more expensive the grease is, the better. Instead, it's the one that matches the working conditions that is the most cost-effective. Choosing the right model can not only protect the equipment but also reduce downtime and maintenance costs.