Have you ever viewed a house for purchase and been impressed until you get to the garage and there’s a huge oil stain right in the middle of the floor? It just seems to me to beg the question, “If they didn’t care about making a mess here, how did they treat the rest of the house?” An ugly stain on the concrete just really looks bad. To guard against this problem the best alternative is to apply garage floor sealants.
Even though concrete is very hard, by nature it is actually porous if not sealed. You see this when a person pours a concrete slab over an artesian well. The water will seep up through the floor and there is nothing you can do other than find a way to drain the well away from the structure. Like water, oil will also permeate the concreted and when that happens it can be very difficult to remove.
If you are planning to apply a garage sealer then be sure to get all this petroleum up and out of the surface or you will not be happy with the results. This can be a difficult process but it is possible. First, use soap and water to scrub the floor as well as you can. A good 18” floor broom works well for this because you can apply a lot of downward pressure quite easily. I always buy the brooms which have the braces on the head because they stand up a lot better.
The next step is to use a good degreaser to lift the oil and other contaminants out of the surface. This requires applying the cleaner, letting it sit for a while, and then cleaning again with soap and water. Be careful where to runoff from the degreaser project goes as it can stain other concrete surfaces. Use plenty of water to wash it on down into the street.
Once the floor is completely cleaned, let it set overnight to dry and then apply the sealer.