Selected Answers

From Arun Gopinathan of BASF Construction Chemical on October 29, 2013:
Step 1: Spray water to see if it is forming beads, ...read more Step 1: Spray water to see if it is forming beads, showing oil contamination. Step 2: Find out how long it has been exposed to oil. If the oil stain is only superficial, use a industrial quality degreaser to clean the area. Step 3: If the oil has impregnated  the concrete, use hot air/ flame method for heating the oil and burning it out. There may be some spalling of concrete due to the intense heat, but  without the heat, the oil will not rise to the surface to be burned off. Step 4: Apply solvented, penetrating, low-viscosity epoxy primer after the burning off but before the concrete has cooled off completely, so then it impregrnates deep and seals and stabilizes the surface. Step 4: Carry on with the recommended coating system on top.

From Kevin Sigourney of PROSOCO, Inc. on August 29, 2013:
Grind the concrete slab open with a diamond grinde ...read more Grind the concrete slab open with a diamond grinder/polisher and apply a liquid hardener/densifer. A clear penetrating sealer and stain repellent can be applied as well. This option would require less maintenance and you would avoid the slip and slide nature of garage floors with patches of peeling paint that can become slick to walk on.

From Carl Thompson of Hill Brothers on August 28, 2013:
1) I would put diatomaceous earth or kitty litter ...read more 1) I would put diatomaceous earth or kitty litter on the oil spots and leave overnight. Clean off the next day and this removes the superficial oil residue. 2) I would wash with a solution of TSP to clean deeper stains. 3) If possible, I would power wash the surface and let it dry at least 24 hours. 4) I would acid etch the concrete with with something like Desert Brand Etch Off which doesn't cause corrosion or harm plant life. 5) I would power wash until a pH of 7 is reached and let it dry 24-48 hours depending on weather. Now you should have a perfect substrate for your new coating.

From Bonny Njimogu of Construction Specialist Services Ltd. on August 28, 2013:
Oil, grease, bitumen, or rubber adhesives could be ...read more Oil, grease, bitumen, or rubber adhesives could be problematic when encountered in surface preparation, whether on concrete, steel,wood, or other substrates. Great care should be exercised in handling these contaminants. 1) Cover the oily surface with absorbent powder or proprietary absorbent towels. Sweep off and clean. 2) Degrease and wash surface with industrial grade cleaning agent. 3) Scrabble the surface to remove the floor's top skin. Sandblasting may not be appropriate in case of penetrated oil. 4) Clean and wash off thoroughly, and then introduce new self-leveling cementitous overlay. 5) Conduct your moisture test and apply your coating as recommended.

From Thomas Selby of Retired on August 28, 2013:
Check the floor for moisture with the plastic shee ...read more Check the floor for moisture with the plastic sheet method, ASTM D4263, if the floor is at ground level. Clean the floor with an industrial cleaner-degreaser. After cleaning, the floor should have a "break free" appearance with no areas of beading which would indicate oil or grease still present. Allow the floor to dry and proceed with the surface preparation method recommended by the coatings manufacturer.

From Mike McCloud of Amex on August 27, 2013:
Clean or blast as well as possible and apply a pre ...read more Clean or blast as well as possible and apply a pre-prime sealer. I have had great luck with Devoe 167 and Sherwin Williams 920.