I want to remodel the garage into an extra bedroom. I think we'll cover the concrete with laminate, but until we get the money for that, I want to get out the oil stains. There all kinds of detergents including TSP, but I was told there's a motorized deep cleaner that you can rent for the job. Do you know about them?
Rod H. ~ San Diego, California
Hi Rod, the only type of deep cleaner I might recommend for the project is a commercial pressure washer. You may need a unit that has a little more pressure than those typically sold at hardware stores and home improvement retail centers. I would think you are going to need a pressure washer that can produce at least 2,500 p.s.i., and it wouldn't hurt to rent one with a 3,000-4,000 p.s.i. capability.
I would try it with some regular cleaners first, as they are a little safer to work with. You don't want to rent a grinder or any machine which might scratch or damage the concrete surface. There is a possiblity that you might not be able to remove all of the oil stains with a pressure washer and cleaner, but you should be able to get them to where they are much less noticeable. Concrete is porous and oil that has been allowed to remain in place until it dries can be very difficult to remove completely.
If the results are not what you are looking for when using the regular cleaner, you may want to try the trisodium phosphate (TSP) or a muriatic acid. Be extremely careful when using either of these products as they are very toxic. Wear gloves, eye protection, and protective clothing, and keep in mind that these are flammable products. I would open all doors to your garage and let it ventilate to get all fumes out before using either of these products and then let the garage continue to ventilate after using them. Make sure you dilute and use the products as per the manufacturers' recommendations. It might not hurt to stop at a fire station around your home in San Diego to see if you can borrow a respirator to use when using the TSP or the acid.
There is a possibility that some of these products might alter the color of your garage concrete, but if you are planning on putting down a floor covering in the future when it becomes a home addition, it should not be an issue. You should be able to rent the commercial pressure washer at most tool rental locations, there are probably quite a few of them around San Diego, California.