You will need to strip the house down to bare wood if you want to go to an oil based stain. You can put latex on top of oil, but not oil on top of latex. Make sure that the ”oil” based stain you are going to use isn’t a plant oil type stain, aka, linseed, safflower, etc. You will still experience harder damage on the sunny sides of the home even with an oil stain. All stains need maintenance every 3 years or so. More often on the heavy exposed sides.