We just moved in to this house with a Stucco exterior and we would like to paint it another color. I can not tell if the paint on the house is oil based or water based. I tried the acetone test but nothing came off on the paper towel. Do I need to use a solvent based paint? Do I need to prepare it a different way?
When in doubt use a good primer. The overall prep is the same, wash the stucco to remove any dust or dirt and prime to seal the surface. Any good exterior acrylic primer will work well. Two that come to mind are Zinsser Bulls Eye 123 and Gripper, both are 100% acrylic.
After the priming go ahead and finish the prep and paint.