Perhaps someone has already suggested this. Try pinesol if it is still on the market. It is a waterbased microemulsion, probably dipentene, a mixture of d-and l-Limonene. I formulated a microemulsion of this with water and it really cut through heavy oil deposits on heat exchangers at refineries. Of course, mine was industrial strength. And it doesn't smell bad unless you hate the smell of pine.
Apply it, let it soak in for 15-20 min, then hose it off. My formulation worked great on oil spots on my drive way, but here again. It was industrial strength with about 30-50% dipentene (pine oil).
You have gotten a lot of great suggestions, but there is one yet missing. Sometimes a job can require special equipment and considerations. You mentioned the stains were in a garage, I believe. While many suggested power washing with strong soaps or detergents, this may not be practical if your garage has finished or semi-finished walls. Power washing is inevitably going to splatter on the walls, etc. Thus you would have to spend considerable time preparing the walls by covering them with plastic etc. And even then, there is no guarantee that you will not get water/soap solution running under the walls.
While I am an avid and life long DIY'er, for this one, I think, I would call in a pro. I would get an estimate from Stanley Steamer, or one of the fire/water clean up firms. This would likely be a small job for them. They will have the specialized machines and experience to steam/vacuum the floor area to a degree that you as a home owner are unlikely to have. You must have reasonable expectations on what results you will get, however. Chances are nothing is going to make the concrete slab look as if it had been freshly poured; undoubtedly it will look better, just not new.
i am enjoying reading all the responses to the question! to superimpose to everything already suggested, it is also good to acquire a p95 face mask for around $8 from your local paint store. these have a little ventilator so can comfortably cover your mouth and nose for reasonable periods of time. it is critical that you obtain the p95 and NOT n95 ! the p95-rating means that it will stop 95% of particulates, including petrol-based. here is the cdc hyperlink CDC - NIOSH-Approved P95 Particulate Filtering Facepiece Respirators - Suppliers List personally, i have been using these masks for years, and are also useful during cleaning and changing kitty litter!
Dear Ann Smith
I translate your Question to Arabic
Is it safe to use acetone to clean a concrete garage floor
هل هي آمنة لاستخدام الأسيتون لتنظيف أرضية المرآب الخرسانية
لقد اشتريت منزلاً به أرضية جراج مغمورة بمواد كيميائية للسيارات. يبدو أن ميكانيكي سيارات كان يعمل في المرآب ، وترك كل شيء يتسرب على الأرض لمدة 30 عامًا ولم يحاول مطلقًا تنظيف أي انسكابات. الكلمة تجعل رائحة المرآب سامة وأي شيء يمس الأرض يأخذ رائحة كريهة للغاية. لقد جربت كل منظف مصمم لغرض تنظيف أرضية مرآب خرساني والكثير من الحلول المنزلية أيضًا ، مثل صابون الفجر ، ولا شيء يزيل أي شيء من الخرسانة. أعلم أن الأسيتون قاسي وليس الخيار الأول بسبب الأبخرة ولأنه سيجعل الخرسانة أكثر مسامية ، لكن علي إزالة المواد الكيميائية السامة من أرضية المرآب. أعلم أن البرك الخرسانية الملطخة يتم تنظيفها باستخدام الأسيتون ، لذلك حصلت على الفكرة.
ما يقلقني هو سلامة خلط الأسيتون مع المواد الكيميائية للسيارات مثل الزيت والبنزين وسائل النقل ، سائل الفرامل ، وما
الى ذلك اريد ان اتاكد
I purchased a house that has a garage floor that is soaked with car chemicals. It looks like a car mechanic worked in the garage and just let everything spill on the floor for 30 years and never attempted to clean up any spills. The floor makes the garage smell toxic and anything that touches the floor takes on the very offensive smell. I have tried every cleaner formulated to for the purpose of cleaning a concrete garage floor and lots of home solutions too, like Dawn soap, and nothing removes anything from the concrete. I know acetone is harsh and not a first choice because of the fumes and because it will make the concrete more porous, but I have to remove the toxic chemicals from my garage floor. I know concrete pools that are stained are cleaned with acetone so that is where I got the idea. My concern is the safety of acetone mixing with car chemicals like oil, gasoline, transmission fluid, brake fluid, etc. I want to be certain not to cause an explosive chemical reaction or a fire. So, is it safe to use acetone to remove the chemicals from my concrete garage floor