Our product is not designed to be used over oil based stains, urethanes, or paints. We recommend the use of water based stains. Oil based products create adhesion and finish issues.
If an oil based stain has already been applied the official recommendation would be to strip and re-stain with a water based product. As an alternative option we have had customers report successfully top-coating oil base stained surfaces with water based polyurethane and then use our product on top of the water based polyurethane.