Opportunities and Challenges with Polyalkylene Glycol for Engine Oil Application

Base oil plays an important role in engine oil formulation in delivering overall performance attributes in addition to additives. Non-traditional base oil like polyalkylene glycol (PAG) did not get much attention in the past for formulating automotive engine oil. This investigation explored PAGs for enhancing engine oil performance primarily for fuel economy benefit over traditional mineral oil-based formulations. This paper highlights key findings from an extensive investigation, parts of which were published in detail elsewhere, and identifying opportunities and challenges. Several PAG chemistries were investigated depending on their feedstock material. Friction performance was evaluated by several methods starting with laboratory bench tests to engine components to chassis roll dynamometer tests. Durability was also evaluated from laboratory bench tests to engine components to ASTM sequence tests. The investigation revealed that significant friction reduction or fuel economy gain can be achieved with PAG oil but wear protection capability, piston deposit, and varnish require much improvement requiring identification/development of additive components. A few alternative routes for performance improvement are suggested.