For starters, automakers want reduced oil consumption and more fuel economy from the new spec than present oils provide. For starters, automakers want lower rates of oil consumption and greater fuel economy from the next generation of oils than they've received from this generation. Because the choice of motor oil basestock affects the oil consumption and fuel economy of the finished motor oil, industry insiders are calling the new spec a basestock battle.
Synthetics own the high ground on both counts.
Reduced oil consumption Reduced oil consumption allows automakers to use less expensive materials for catalytic converters. High oil consumption contributes significant hydrocarbons to the emissions stream. Reducing oil consumption also allows automakers to extend oil drain intervals by helping the oil retain its ability to lubricate and protect after exposure to high temperatures.