Formation of nanoemulsion with long chain oil by W/O microemulsion dilution method

•Long chain oil nanoemulsion was formed by W/O microemulsion dilution method.•Nanoemulsions with different charge, even positive charge, were formed W/O microemulsion dilution method.•Thermodynamically stable W/O microemulsion, can be diluted to nanoemulsion on demand, is an alternative to nanoemulsion.•Easy-to-prepare systems in this work show important application, especially in water-based drilling fluids.