Yang, K., Fletcher, K., Styer, J., Lam, W. et al., "Advanced Lubrication - Enabling and Protecting Turbocharged, Direct Injection Gasoline Engines for Optimum Efficiency," SAE Technical Paper 2016-01-2275, 2016, doi:10.4271/2016-01-2275.
There has been a global technology convergence by engine manufacturers as they strive to meet or exceed the ever-increasing fuel economy mandates that are intended to mitigate the trend in global warming associated with CO2 emissions. While turbocharging and direct-injection gasoline technologies are not new, when combined they create the opportunity for substantial increase in power output at lower engine speeds. Higher output at lower engine speeds is inherently more efficient, and this leads engine designers in the direction of overall smaller engines. Lubricants optimized for older engines may not have the expected level of durability with more operating time being spent at higher specific output levels. Additionally, a phenomenon that is called low-speed pre-ignition has become more prevalent with these engines. While more pre-ignition may be expected with highly-boosted engines, an especially destructive version of this has been found to be related to some of the essential compounds that comprise the lubricant additive package. Newly introduced OEM specifications have been designed to anticipate the needs of these downsized, down-speeded, turbocharged direct injection engines. New areas of protection include: low speed pre-ignition, enhanced protection against turbocharger deposits, and timing chain wear. Since lubricants must still protect and enable many other items associated with durability like sludge, piston deposits, wear, and resistance to oxidation, we discuss a holistic formulation strategy that ensures a maximum level of engine protection and oil durability to enable the highest degree of fuel economy.