The instant disclosure provides a process for preparing a lubricant or fuel additive mixture where an oil of lubricating viscosity or fuel are blended with additives that are mixed via an acoustic mixer. The additives and oil of lubricating viscosity or fuel can mixed together or any component of the lubricant or fuel additive mixture can be mixed separately prior to mixing to form the final lubricant. The process provides for continuous mixing to form lubricant and/or fuel additive mixture final products.