SYNCHROMAX® - Royal Purple Synthetic Oil Royal Purple® Synchromax® is recommended for manual transmissions that specify an automatic transmission fluid or other light-viscosity oil. It is also ideal for transfer cases and 2-cycle motorcycle gear boxes that specify light-viscosity lubricants. Royal Purple Synchromax Manual Transmission Fluid Synchromax is a synthetic manual transmission fluid designed to increase performance and expand the life of your manual transmission. Thus improves shifting, reduces gear noise and increases power transfer to the wheels. As a performance transmission fluid, it also lowers operating temperatures and provides outstanding wear protection.