An oilhead is the name used for BMW motorcycle engines that advertise the use of oil cooling to transfer some of the heat from the engine to the atmosphere.

The concept of oil-cooling engines is not revolutionary or even new, since engine oil has always had the effect of carrying away heat, usually for it to be dissipated to the atmosphere via a sheet steel or finned cast-alloy sump or rocker box. But modern variations (eg Suzuki's GSX-R 750) employ an oil-radiator to cool the oil, and the forms of circulation introduced encourage the engine oil to heat up more quickly with benefits to engine life, economy and perhaps performance.

Long hair is a hairstyle. Exactly what constitutes long hair can change from culture to culture, or even within cultures. For example, a woman with chin-length hair in some cultures may be said to have short hair, while a man with the same length of hair in some of the same cultures would be said to have long hair.

Scientists view long hair as playing a large part in natural selection among many species, since long, thick and healthy hair or fur is frequently a sign of fertility and youth. As hair grows slowly, long hair reveals several years of a person's health status and reproductive fitness. Hair length is significantly correlated with female attractiveness, as rated by men as well as women. Hair length and quality can act as a cue to especially a woman's youth and health, signifying reproductive potential. The prevalence of trichophilia (hair partialism or fetischism) is 7% in the population, and very long hair is a common subject of devotion in this group.

Ways of life often viewed as more rigid, such as soldiers and religious cultures, often have explicit rules regarding hair length. For example, Buddhist monks shave their heads as part of their order of worship. Even outside religious structures, cultures often associate male long hair with ways of life outside of what is culturally accepted. Subservient cultures, for example, are sometimes detected by their rulers through hair length, as was the case with the Gaelic Irish under English rule and the Moors under Spanish rule in Medieval Spain.