The most often used grease is ______ because it provides excellant lubrication under moderate loads and also at high temperatures and speeds.

• A. Lithium
• B. Sodium
• C. Calcium
• D. Polyurea

Answer: (A)

Grease selection hinges on the thickener chemistry, which determines how well the lubricant film stays intact under heat, speed, and load. Lithium grease uses a lithium soap thickener that provides a stable lubricating film across a wide temperature range, so it performs well in moderate loads and also when temperatures and speeds are higher. It adheres well to metal surfaces, resists water washout, and has a good drop point, meaning it won’t break down as the bearing gets hot. This combination makes it a versatile, economical all‑purpose choice for many bearings. Other greases have strengths in specific conditions—sodium and calcium greases may offer different temperature or water resistance characteristics, and polyurea greases can handle high temperatures and long life—but they don’t offer the same broad balance of film strength, washout resistance, and cost that lithium grease provides for everyday use.