Synthetic oil is a lubricant consisting of chemical compounds that are artificially made (synthesized). Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials. Synthetic oil is used as a substitute for lubricant refined from petroleum when operating in extremes of temperature, because, in general, it provides superior mechanical and chemical properties than those found in traditional mineral oils. Aircraft jet engines, for example, require the use of synthetic oils, whereas aircraft piston engines do not.

Long before the use of petroleum oil, rendered animal fat, whale oil and vegetable oil were used as lubricants. These oils are considered synthetic oils by the modern definition because they were man-made from ingredients in the environment. It wasn't until the 1860's that petroleum oil became a popular lubricant.

In the 1930's, Dr. Hermann Zorn of I.G. Farben Industries in Germany began to search for lubricants with the properties of natural oils but without the tendencies to gel or gum when used in an engine environment. His work led to the preparation of over 3500 esters in the late 1930s and early 1940s including diesters, polyolesters, and banana oil.

Earl Richard Stewart, Jr. (October 15, 1921 – July 11, 1990) was an American professional golfer who played on the PGA Tour in the 1950s and 1960s; and was a college head golf coach in the 1970s and 1980s.

Stewart was born in Dallas, Texas. He attended Louisiana State University and was a member of the golf team. In 1941, he won the NCAA Championship, and led the Bayou Bengals to a share of the NCAA team title in 1942.

Stewart had three wins in PGA Tour events during his career. His first win came in 1953 at the Greater Greensboro Open. He would win the Ardmore Open later that year. His best finishes in major championships were T10 at the 1952 U.S. Open and T15 at The Masters in 1953. Like many professional golfers of his generation, Stewart earned his living primarily as a club pro. His third and final win on the PGA Tour, the 1961 Dallas Open Invitational, came on his own course at the Oak Cliff Country Club.

Stewart was the head golf coach at Southern Methodist University from 1975–1987. He coached both the men's and women's teams. Men's golf was dropped by the university in 1980. He won a national championship with the women's team in 1979. One of his students was future two-time U.S. Open and PGA Champion Payne Stewart (no relation). In 1987, he was inducted into the National Golf Coaches Association Coaches Hall of Fame for his role as a women's collegiate golf coach at SMU.