AMSOIL Synthetic Motor Oils Increase Fuel economy. Good Video on what happens to Amsoil 5-30 motor oil and conventional 5-30 motor oil when exposed to -40 degrees. AMSOIL still flows AND conventional oil barely moves! This article discusses in depth how synthetic oil increases fuel economy without compromising wear protection and why synthetic oil offers better fuel economy than conventional oil. AMSOIL lubricants save money on fuel!