The 36-year-old veteran says he will try to convince the star Mexico international to join the newly promoted Liga side this summer.
The 24-year-old Dos Santos, who was relegated with Mallorca this year, is reportedly seeking a move away from the Islanders during the summer. Valencia, as well as MLS outfit LA Galaxy, are said to be monitoring the former Barcelona starlet as well, but ex-international teammate Franco says he will try to persuade Dos Santos to join newly promoted Villarreal from Mallorca, where he is under contract until June 2016.
"I have not spoken with him, but I have spent lots of time with him in the Mexico team and I can say he is a great player," Franco told Marca. "Gio is fast, strong and has some great qualities, and if I speak to him I will try to convince him to join Villarreal."
Franco, who represented Mexico in the 2006 and 2010 World Cups, enjoyed a three-year spell with the Yellow Submarine from 2006 until 2009, netting 20 goals in more than 100 appearances. He last played for the Chicago Fire in MLS, making three appearances after joining the team from Pachuca last summer.