Oscar, who moved to Stamford Bridge last year from Internacional, has admitted that the duo have helped him settle into life in London.
"We get along very well on and off the pitch," Oscar told the club's official magazine. "My wife and sister are with me now, so I have been seeing London with them, but I spend a bit of time with David and Ramires.
"We might go out for dinner at a nice restaurant together with our families or go and see some sights because there are so many here in London."
Luiz added: "Yes, I have a great friendship with them both. They can be more shy than me but, because I know them and I can speak English a little bit better than them, if it is difficult for them to express themselves, I can try to help."
Meanwhile, the Blues are preparing to take on Steaua Bucharesti in the Europa League this week.