@Rebbecaxock 1) Define what is “large” 2) Why would you even want to do this? Oil reduces efficacy of surfactants (aka less foam). Surfactants have a hydrophilic head and a hydrophobic tail. They “surround” oil to create a micelles (they “connect to the oil” via their tails). How do shampoos and shower gels work? They connect their hydrophobic tails to the sebum (oils on your skin) and help to rinse it off. Add more oil and all tails are “busy forming micelles” instead of cleaning your skin. It’s a simplified explanation, but my point is, you just don’t want to add too much oil to your shampoo, or it will not do the job. Regarding plant extracts, need to know what exactly you are using to provide any comments.