Newton-John, 71, is wearing a white blouse, sneakers, yellow skirt and cardigan in the image.
Travolta, 65, is in a black T-shirt, jeans, boots and leather jacket.
They are also scheduled to take part in similar events in Tampa on Saturday and in Jacksonville on Sunday.
Grease is based on a Broadway show about a rocky teen romance between a wholesome new transplant to Rydell High and the school’s resident bad boy in 1950s California. It has been adapted countless times by professional, community and school theaters over the past four decades.
A live TV production aired on Fox in 2016.