How do I clean oil stains from my concrete garage floor in NB?

Oil stains on a concrete garage floor require a degreaser-based approach, and the sooner you treat the stain, the better -- fresh oil is far easier to remove than oil that has had weeks or months to penetrate into the concrete.

Concrete is porous, and motor oil, transmission fluid, and other petroleum products penetrate readily into unsealed concrete floors. For a fresh spill (hours old), absorb as much as possible with kitty litter, sawdust, or oil-dry absorbent, then sweep and dispose. The absorbent material will capture the surface oil before it migrates deeper into the concrete.

For set stains on NB garage floors, the most effective approach is:

Start with a commercial concrete degreaser or trisodium phosphate (TSP) solution. Apply the degreaser concentrated to the stain, work it in with a stiff brush, and allow it to dwell for 15-30 minutes. TSP is available at NB hardware stores and is particularly effective on petroleum stains. Scrub vigorously, then rinse thoroughly with hot water. Repeat if the stain persists -- multiple treatments are usually needed for old, deep stains.

For stubborn or old oil stains, a poultice method works well: mix an absorbent material (pool filter sand, diatomaceous earth, or commercial poultice powder) with a solvent like acetone or mineral spirits to form a paste. Apply the paste over the stain, cover with plastic sheeting, tape the edges, and leave for 24-48 hours. The solvent softens the oil and the absorbent material draws it out as the paste dries. Remove the dried poultice, sweep, and clean the area with degreaser. This method is particularly effective on deep-set stains.

Biological enzyme cleaners are an eco-friendly option that use bacteria to consume petroleum hydrocarbons. They work more slowly than solvents but are effective for large or diffuse staining and leave no chemical residue. Apply, keep moist, and allow 24-72 hours for the enzymes to work.

For very large or severe oil contamination (floor soaked in oil from a leaking vehicle over many months), the oil may have penetrated too deeply to remove completely. In this case, professional floor coating or resurfacing after deep cleaning may be the practical solution.

After cleaning, seal your garage floor with a penetrating sealer or epoxy coating to prevent future oil and fluid penetration. In NB's climate, a sealed floor also resists the moisture and road salt that gets tracked in through the winter months. Sealing is the single best step you can take to make future cleaning easier and protect the concrete from freeze-thaw damage on the garage apron and at the doorway.