The automobile industry is the major user of lubricants. Engine designs have been continually improved to reduce weight, increase fuel economy, increase power output, and at the same time meet environmental emission guidelines.
Research is ongoing to formulate lubricants to meet the demands of the redesigned engines.
In general, a lubricant must perform nine functions for the efficient operation of the engine. An engine oil must be thin enough when first starting the engine to allow for sufficient cranking speed. The oil must then be able to flow immediately to lubricate vital engine components. Most of the engine wear occurs at start-up before the oil can reach all the engine parts. As the engine is heated, the oil must not become too thin and be unable to provide adequate engine lubrication.