A multi-functional olefin copolymer viscosity index improver and a lubricating oil composition including such lubricant additive that provides improved viscometric properties and helps reduce low speed pre-ignition events at the same time. In one approach, the multi-functional olefin copolymer viscosity index improver is silicone functionalized and includes an acylated olefin copolymer with aminosilane or aminosiloxone pendant or side groups.