Why Oil Ruins Coating Adhesion
Coatings bond by mechanically locking into open concrete pores. Oil fills those pores and creates a chemically incompatible surface layer. New resin lifts off the oil, not the concrete.
What Cleaning Actually Removes
Degreasers pull surface oil. They do not reach oil that has soaked several millimeters into the slab, which is normal in garages more than a few years old.
How Grinding Helps
Diamond grinding removes the top 1/32–1/16 inch of contaminated concrete. For most residential garages this is enough. Heavy commercial and shop floors sometimes need deeper cuts.
When a Test Area Is Worth Doing
If the slab has visible oil saturation across a large area, we grind and prime a small section, let it cure, then peel-test before committing to the whole floor.
When Coating Isn't the Right Answer
A slab that has been an active oil-drip floor for decades may not clean up to a bondable surface. In those cases we recommend a bond-primer test or replacement over an install that will fail.