There are various types of grease, each designed for specific conditions and applications. For instance, lithium grease is popular due to its versatility, excellent performance under high temperatures, and good water resistance. Calcium grease is known for its superior water resistance, making it suitable for marine applications. Synthetic greases, often made from polyalphaolefin (PAO) or esters, offer excellent performance at extreme temperatures and under high load conditions, making them suitable for aerospace and high-speed applications. The selection of grease depends on factors like temperature range, load, speed, and environmental conditions.