Most of it, usually — but not always all of it, and anyone promising otherwise on an old stain is overselling. Oil soaks into concrete rather than sitting on it, which makes this the most expectation-sensitive part of concrete cleaning and stain treatment.
Why oil is different from dirt
Concrete is porous, and petroleum products are excellent at penetrating pores. A fresh drip sits mostly at the surface; a stain that has been recharged weekly by a parked car for two years has soaked deep into the slab.
Water-based cleaning does not touch it — oil and water famously decline to cooperate. Pressure alone actually spreads a fresh stain rather than removing it.
Heat makes it worse. On a July slab, engine oil thins out and travels further into the pore network in an afternoon than it would in a week in March, which is why the same drip from the same car produces a very different stain depending on when it landed.
How porous is your slab, and how old is the stain?
Those two questions decide the outcome before anyone opens a bottle.
Porosity first. A hard-troweled garage floor has a dense, closed surface and holds oil comparatively near the top. A broom-finished driveway has open pore mouths and more surface area. Exposed aggregate is worse again. Age compounds it: new concrete still carries its tight layer of surface paste, while decades of rain, freeze-thaw and traffic wear that layer away and leave the pore structure underneath wide open. An old rural driveway is a much better sponge than it was when it was poured.
Then the stain’s history. A single drip from last month is a surface event. A patch under a daily-parked truck, topped up every week for years, has a reservoir underneath it — and that reservoir is the reason a stain sometimes looks gone at the end of a wash and reappears as a faint shadow two days later. Nothing failed; oil wicked back up as the slab dried.
How to judge it yourself
Wet the area. If the stain vanishes under water and comes back as it dries, you are looking at colour in the pores rather than a film on top, and the treatment is chemical. If the surface feels slick or glossy, there is still free oil at the top and a degreaser will make dramatic progress. If the concrete is pitted, powdery or crumbling in the middle of the stain, oil has been sitting long enough to work on the cement paste and no cleaning will bring that back.
What treatment actually does
A degreaser breaks the oil’s bond with the concrete and emulsifies it so it can rinse. Dwell time matters more than product: the chemistry needs minutes to work into the pores, not seconds. Hot water helps; agitation helps; a second application on old stains is routine.
Fresh stains often disappear entirely. Old, deep stains lighten dramatically — commonly to a faint shadow visible only when you look for it — but the oil that has migrated deepest is beyond the reach of any surface treatment. That is the honest ceiling.
Why dwell and heat do the heavy lifting
An alkaline degreaser works by surrounding oil droplets so water can carry them off, and that reaction happens at the speed the chemistry can travel into the pores. Rinse it after thirty seconds and you have cleaned the top of the stain. Keep the surface wet with it for several minutes, agitate it into the texture with a stiff brush, and you reach the oil that actually causes the colour. What you must not do is let it dry — a degreaser that dries on the slab leaves its own residue and stops working.
Heat is the other lever. Hot water lowers the viscosity of the oil so it releases and flows, and it speeds up the chemical reaction at the same time. It is not necessary on a fresh drip and it is close to decisive on an old one, which is broadly when hot water genuinely earns its place rather than being a line on a sales sheet.
For the worst individual stains there is one more step: a poultice. An absorbent material carrying a solvent is spread over the stain and left to dry slowly, and as it dries it draws oil out of the pores into itself. It is slow, it works on stains nothing else touches, and it is worth doing only where a specific mark matters enough to justify the time.
The order of operations that works
Degrease the stain first, then clean the whole slab uniformly with a surface cleaner so the treated area does not stand out as a clean patch on a grey slab. Then, if you want the result to last, seal — a sealed slab keeps the next drip on the surface where a rag can catch it.
For active drip spots under a daily-parked car, a drip tray costs almost nothing and saves the slab.
The whole slab being the unit of work is not an upsell, it is how the eye works. Remove a stain in isolation and you have swapped a dark mark for a light one; the contrast is what people notice. Concrete displays differences, not absolutes.
What cannot be removed
Say it plainly, because it saves everyone a disappointing morning.
Oil that has migrated deep into an old, porous slab is not coming out with a surface treatment. Concrete that has been softened or pitted under a long-standing stain is damaged, and cleaning exposes that rather than repairing it. Transmission fluid and some hydraulic oils carry dye that stains more stubbornly than motor oil. And any stain sitting under an old failing sealer has to have that coating removed before treatment reaches the concrete at all.
Where the mark matters more than the material — a garage floor you look at every day — the honest answer at that point is not more cleaning. It is a coating or an overlay, and that is a different trade.
How this plays out in Southeast Missouri
Oil staining here is not mainly a suburban garage problem. It is farm and shop staining: hydraulic fluid on a machine shed floor, diesel and gear oil where the tractor sits, a combine parked on the same patch of concrete every autumn. Those fluids are harder to shift than motor oil, and they are usually on old broom-finished slabs that have been drinking them for years. Floor cleaning and equipment cleaning tend to be the same visit, which is why oil work often turns up alongside fleet and farm equipment washing.
Small-town commercial work has its own version. Behind the restaurants and cafes in Marble Hill, Fredericktown or Jackson, the staining on the pad is grease as much as petroleum, it is organic, it smells, and it is the thing an inspector notices — the dumpster pad is what fails an inspection far more often than the kitchen behind it.
The climate adds two complications. Humid summers and heavy tree cover mean slabs dry slowly, so a degreased area can take a day or more to show its true colour, and judging the result too early is the commonest cause of a wasted second treatment. Winter is the other one: freeze-thaw and salted roads open the surface a little more each year, so the same driveway near Patton absorbs oil more readily at forty years old than it did at ten.
Keeping the next stain shallow
The fixable part of oil staining is nearly all about time. A drip caught the day it lands wipes off with a rag and cat litter; the same drip found in October is a treatment.
Sealing is the structural fix, because it keeps oil at the surface where it stays reachable. It also makes routine cleaning quicker and slows every other kind of staining the slab is exposed to, which is most of the argument for sealing a driveway in Missouri. Beyond that: fix the leak, use a tray under a known drip, keep absorbent to hand in the shed, and do not park the same vehicle on the same square metre of a bare slab for a decade if you can help it.
Common questions
Does cat litter actually work?
On fresh oil, yes — it absorbs what has not yet soaked in, and ground fine and worked underfoot it does more than sitting on top in a heap. On a stain that is already days old it does nothing, because the oil it needed to catch is already below the surface.
Why did my stain come back a few days after cleaning?
Oil that had travelled deep wicked back up as the slab dried. It is not a failure of the treatment; it is the treatment finding the ceiling. A second application usually takes the shadow down further, and a third rarely earns its cost.
Can I use dish soap or engine degreaser from a tin?
Both do something, and both fall short on old staining because they are rinsed long before they have penetrated. The larger risk is what comes off the slab: engine degreasers are not all safe on landscaping.
Is it worth cleaning a stain if I am going to seal anyway?
Yes, and in that order. Sealer over a stain traps the colour and fixes it in place, and penetrating sealers do not hide anything — they change how the slab absorbs, not how it looks. Clean, let it dry properly, then seal.
How old is too old?
There is no cut-off date, only depth. A two-year stain on a dense troweled floor can come out better than a six-month stain on a weathered exposed-aggregate drive. Send a photo and say roughly how long it has been there and whether anything still drips, and the expectation can be set before anyone quotes.
Photograph the stain and tell us roughly how old it is — we will give you an honest expectation before we quote. Read more about concrete cleaning and stain treatment →