Lubrication Engineers' Monolec Ultra Syn heavy duty engine oil, No. 8854, comes as a broad-range multiviscosity synthetic oil for diesel engines. Designed to deliver year-round performance, wear protection, fuel efficiency and extended drains. With its synthetic base oil and additive package, this SAE 5W-40 formulation reliably lubricates diesel engines, even in low-temperature conditions, without the shear stability and viscosity problems of conventional diesel engine oils. Its high viscosity index indicates less change in viscosity over a broad operating temperature range and fuel efficiency improvements.