Polyurea lubricant composition with conditionally two and four urea units per polyurea thickener molecule in the presence of a second biodegradable thickener (nanocellulose, cetearyl alcohol) were synthesized. The drop point, penetration, and oil separation and rheological, tribological, and antiwear properties were evaluated. The lubricant composition properties changed depending on the number of urea units per polyurea molecule and content of second biodegradable thickener. Tetraurea-based greases had lower viscosity and better tribological and antiwear properties regardless of the nanocellulose content, confirming that the urea-thickener structure had a decisive influence on the lubricant-composition properties.