grease

Grease is a semi-solid lubricant used to reduce friction in mechanical systems. It consists of a base oil that provides lubrication and a thickener that gives it its semi-solid consistency, often supplemented by additives to improve properties such as oxidation resistance and corrosion protection. Common thickeners include lithium and calcium soaps, with others based on polyurea or clay.

Grease is graded by a consistency scale known as the NLGI grade, which ranges from 000 for very fluid grease to 6 for rigid grease. It is chosen based on temperature range, load, speed, and environmental exposure. Specialty greases include high-temperature variants, marine grease with water resistance, and food-grade greases suitable for equipment in contact with food.

Grease is widely used to lubricate bearings and gears in automotive, industrial, and household applications, particularly where oil lubrication would drain away or leak. It can seal out contaminants and retain lubricant in porous components. Safety and environmental considerations include using food-grade varieties in food-processing environments and selecting low-toxicity formulations for sensitive equipment.

Grease also refers to the 1978 American musical romantic comedy film, Grease, directed by Randal Kleiser and based on the 1971 stage musical by Jim Jacobs and Warren Casey. The film stars John Travolta as Danny Zuko and Olivia Newton-John as Sandy Olsson, and features songs such as You’re the One That I Want and Summer Nights. It achieved major box office success and has had lasting cultural impact, including remakes, stage revivals, and lasting popularity of its soundtrack.