Low-Speed Pre-Ignition (LSPI) is one of the key issues for developing highly boosted direct injection spark-ignition engines for passenger cars. In this report, based on the hypothesis that LSPI is triggered by ignition of droplets containing lubricant, a constant volume chamber was used to observe and comprehend ignition characteristics of a lubricant. In addition, a multi-dimensional CFD code was utilized to determine chemical ignition characteristics. The result shows that the lubricant has extremely high ignitability. Thus, it is probable that the droplets containing lubricant are a major cause of LSPI.