F+L Week 2019 | Vincent Gatto | Approaches for reducing corrosion of engine lubricants containing friction modifiers
Ashless friction modifiers and organo-molybdenum compounds are well known for their fuel economy improvement benefits and anti-wear activity in lubricating oils and greases. In certain formulation styles, these compounds can contribute to moderate, or even severe, copper and lead corrosion in engine oils. In sensitive applications this can limit the use of friction modifiers and their treat level. There is a strong need in the lubricant industry for strategies to reduce the corrosive nature of friction modifiers and especially organo-molybdenum products so that higher treat rates may be employed and their use can be broadened. In this presentation, two strategies for reducing the corrosive nature of friction modifiers in engine lubricants will be presented. The first involves a formulation approach where novel corrosion inhibitors are used to passivate metal surfaces, preventing the redox reactions that result in corrosion. The second is to design totally new organo-molybdenum compounds that perform similar to the existing products but have a much lower propensity for corrosion. Examples will be presented utilizing both of these approaches as well as the advantages and disadvantages of each.