The main focal point of this chapter is to divulge the tribological properties and best application of ionic liquids (ILs). Specifically in the petroleum-based lubrication industry and energy transfiguration process, oil add-ons have been reporting the best applicability of ionic liquids (ILs). The much-influenced counterparts of ILs have been extremely reported to design efficient lubricating oil with the use of ILs. The specific type of ILs which are halogenated and non-halogenated synthesized was ethyl ammonium nitra is also revealing themselves as the best corrosion inhibitors for studying the tribology on different metal surfaces. In addition, the performance of ILs as oil-additive has been giving good results in terms of tribological performance. The main feature which has to mold the performance of the tribological property, is the modification of anion in ILs. This all enhances the effectiveness of lubricant and oiladditive properties. The main reason behind the corrosion and formation of thin films over metal surfaces is also discussed in detail using different types of ILs and metal surfaces.