quote:
The GF-5 Fuel Economy Panel identified technical issues and concerns with low viscosity engine oils, including oil film thickness, oil pressure, piston and valve train wear, and customer acceptance of "thinner" oils. The panel noted that although there was some computer modeling evidence that suggests that significant fuel economy benefits could be secured by using lower viscosity oils, this could be at the expense of engine oil durability. The panel explored the topic of how fuel economy could be improved through a balance of performance additives, such as antioxidants.