Engine oil sits on a surface and soaks in slowly. Fuel does something different: diesel and petrol are solvents, and on a bitumen-based surface they actively dissolve the binder holding the drive together. That is why a fuel spill on tarmac is not really a staining problem at all — it is chemical damage on a clock.
This guide covers what to do in the first hour, which is when almost all of the outcome is decided, and what is realistically recoverable afterwards. It applies to jerry can overspills, leaking fuel lines, filled-up mowers and the classic caravan or generator refuel that went wrong.
First: safety, then containment
- Petrol vapour is heavier than air and ignites easily. No engines, no smoking, no doorbell-style electrical switches near the spill until it has fully dispersed.
- Ventilate and keep people and pets away from the area, especially in an enclosed carport or garage.
- Do not hose it. Water spreads fuel over a wider area and pushes it into joints, then carries it to a drain.
- Stop it reaching a gully, a soakaway or a watercourse. Fuel entering surface water drainage is a pollution matter, not just a nuisance.
- Dam the edge of the spill with dry sand, cat litter or soil to hold it in place before you do anything else.
Absorb before you clean
Cover the whole spill generously with a dry absorbent — proprietary granules, cat litter, dry sand or sawdust all work. Do not scrub it in. Let it sit long enough to draw fuel up out of the surface, which on porous paving means at least a few hours and often overnight.
Sweep up the saturated absorbent carefully and bag it. Fuel-soaked granules are not household waste; they need to go to a household waste recycling centre that accepts contaminated absorbents. Check locally before turning up with a bag of it.
Repeat with fresh absorbent if the surface is still darkened and smelling strongly. Two or three cycles on a heavy spill is normal and is far more effective than moving straight to washing.
What each surface does under fuel
- Tarmac: the worst case. Fuel softens the bitumen, and the affected patch can go sticky and then sink. Cleaning removes the residue but cannot restore dissolved binder — a damaged patch needs cutting out and repairing.
- Concrete: porous, so fuel soaks in and can leave a shadow plus a lingering smell for months. Recoverable with degreasing and poulticing, but rarely perfectly.
- Block paving: the fuel goes into both block and joint sand. Often the practical fix is removing the contaminated sand entirely, degreasing, and re-sanding.
- Imprinted concrete: if it is sealed, the sealer takes the hit and may soften or lift. That is actually good news — the coating did its job — but the patch will need resealing.
- Resin bound: fuel can attack the resin binder in a concentrated spill, leading to localised stone loss. Prompt absorption really matters here.
- Natural stone: usually survives with careful degreasing, though a light shadow can persist in more porous stone.
Cleaning the residue properly
Once the bulk is absorbed, use an alkaline degreaser suited to exterior paving rather than washing-up liquid. Apply it neat to the stain, agitate with a stiff brush, and give it dwell time — degreasers work by lifting hydrocarbons off the substrate, and that takes minutes, not seconds.
Hot water rinsing is substantially more effective than cold for anything hydrocarbon-based, because warmth reduces viscosity and lets the residue release. This is one of the situations where a hot water machine genuinely outperforms a cold one rather than just being faster.
For a deep stain in concrete or stone, a poultice is the tool that actually works: mix an absorbent powder with a solvent or degreaser into a paste, spread it thick over the stain, cover it, and let it dry out slowly over a day or two. As it dries it pulls contamination up out of the pores. It can take several applications and it is worth the patience.
What not to do
- Do not jet wash a fresh fuel spill — it atomises fuel, spreads the contamination and drives it into the joints and base.
- Do not use a turbo nozzle to try to scour the mark out; on tarmac you will strip the surface and make a worse patch.
- Do not apply a sealer over a fuel-contaminated area. It will not adhere properly and will fail in that spot.
- Do not tip the residue or the washings down a gully; use absorbent and dispose of it properly.
- Do not assume the smell means the job is unfinished — a faint residual odour can linger in porous concrete long after the surface is chemically clean.
When it is a repair, not a clean
If the surface has gone soft underfoot, if a thumb pressed into the patch leaves a mark, or if the area has visibly slumped, you are past cleaning. That is dissolved binder and the honest answer is a saw-cut patch repair. We will tell you that rather than take money for a wash that cannot work.
On block paving, a small number of severely contaminated blocks can be lifted, turned or replaced far more cheaply and effectively than they can be cleaned. If you have spare blocks from the original installation, this is the moment they earn their storage space.
For everything short of that, a professional degrease with hot water plus a full clean of the surrounding area usually brings the drive back to a single consistent appearance, which is often what matters more than removing every last trace of the shadow.