Oil stains are the stain property managers ask about most, and the one that most often survives a regular wash. Parking stalls, garage decks, drive-thru lanes, loading docks and dumpster pads all collect them. They make a well-kept property look neglected, and fresh ones are slippery.
There is no single product that fixes every oil stain. What works is understanding why oil is so stubborn on concrete, then treating it in the right order.
Why oil is so hard to remove
Concrete looks solid, but it is porous, more like a hard sponge than a sheet of glass. Oil does not sit on top of it. It soaks in.
- Heat drives it deeper. Florida sun warms the slab, the oil thins out and works further into the pores.
- Time sets it. Older stains darken and harden as they age and collect grime, which makes them harder to lift.
- It comes back. A stain can look gone after cleaning, then reappear over the next few days as oil from deeper in the slab wicks back up to the surface. This is why one quick wash often disappoints.
What does not work
- Cold water at high pressure on its own. It cleans the surface around the stain and can spread the oil, but it barely touches what has soaked in.
- Hosing it away. In Orlando, wash water with oil in it is not allowed to run into storm drains, which flow to the city's lakes untreated. It is not acceptable to wash it into landscaping either.
- Kitty litter on an old stain. Absorbents are excellent on a fresh spill. On a stain that has been there for months, there is nothing left on the surface for them to absorb.
What does work
The approach is chemistry first, then heat, then recovery.
- Degreaser with dwell time. A degreaser suited to petroleum is worked into the stain and given time to break the oil down. Rushing this step is the most common reason a stain survives.
- Hot water. Heat thins the oil so it releases from the pores. Our equipment runs water at 200 degrees or more for exactly this reason.
- Even surface cleaning. A rotary surface cleaner lifts the loosened oil evenly, so the stall does not end up cleaner in the middle than at the edges.
- Recovery. The dirty water is collected rather than rinsed away.
- Repeat for deep stains. A stain that has soaked deep may need a second treatment, or a poultice left on it to draw the oil out over time.
Rust is a different stain and needs different chemistry. Orange staining near sprinklers or under metal fixtures will not respond to degreaser, so it is treated separately.
What to expect from an old stain
Be wary of anyone who promises every stain will disappear completely. Fresh and moderate stains usually come out fully. A stain that has baked into the concrete for years may lighten a great deal and still leave a faint shadow. A good contractor tells you which is which before the work starts.
Keeping stains from coming back
- Clean up fresh spills fast. Blot and absorb them while they are still on the surface. The City of Orlando recommends dry cleanup methods before any washing.
- Seal the concrete. A sealer makes the surface less porous, so future oil sits higher and lifts more easily.
- Schedule it. In busy parking areas, a regular oil spot treatment between full cleanings keeps the worst stalls from building up.
How we handle oil stains
Green Earth Power Wash Orlando removes bonded oil and grease from parking lots, garages, dumpster pads and walkways across Orlando and Central Florida, using hot water, the right chemistry and wash water recovery. See our oil stain removal and parking garage pages, or request a free estimate.