I have a huge contact riding on getting this stain up, I’ve tried EBC 50/50 and straight, red degreaser, AWESOME, and LYE (sodium hydroxide) @ 1 cup/gallon all direct applied, with 200* heat and it’s not budging one bit. Property mgr says it’s “cooking grease” My next step is the torch method, but if anyone else has a suggestion I’m definitely open. The torch almost always works but it’s REALLY RISKY, especially with a $50k contract depending on it😳.
You could take the top layer off if the tourch doesn’t work with acid. But you’d have to do all of it.
Most likely you will not get it all up in a single cleaning. I do a lot of restaurants, and it usually takes 3-4 monthly cleanings before the back pad/dumpster area starts to look really good (yeah, it looks really good after the initial cleaning from a sh*t stain that is usually is before I clean, but the stains themselves usually take multiple cleanings to really work them out).
I would try 2 lb hydrox, 1 cup TSP, 1 cup dawn with 1 gal water in a pump up - if you have some EBC - throw a cup or two of that in as well. Spray, scrub with a stiff bristle deck brush, Spray, scrub, spray scrub, spray scrub. Let soak in for 30 minutes total before rinsing. Keep misting to keep it wet - don’t let it dry out. Rinse with really hot water.
You can try a poltice method. I know Prosoco makes one. If you don’t know anything out it, look it up. It is a bit of a time consuming project (repeated visits back to site for each step) and may take several application processes but it can work if time is allowed.
I may be the lone ranger on an island by himself, but I really do not think acid with solve the problem. Acid does not break down oils, caustics do.
I also don’t know about the torch. Just seems to me you will burn the concrete and make it worse with a black mark. I keep this on the Facebook groups, but until I did it myself on a test site (not a customers site) and got the process down, I would be weary of doing it live inexperienced.
BTW - where you located?
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I’m in Conway, AR. I’ll try stronger hydroxide, I use 1lb per gallon to downstream @ restaurant concrete, so 2lb/gallon seeme really HOT. 
. But I’ll try it in the morning before the torch. A propane weed burner won’t burn or blacken the concrete but it you get it just a bit too hot it will start popping little chips out, and this is a bad place for that to happen! I scrubbed like crazy and let it dwell about 20 min each time. Then blew it dry with a backpack blower bed the next application.
You need potassium hydroxide. Not guaranteed to get it up 100% but it’s a step in the right direction. I mix sodium and potassium hydroxides.
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This might not work but I have found f9’s efflo to clean some really weird things despite its intended use as an efflorescence remover/calcium build up. It seems to have a mild version of muriatic acid but works better. I use it full strength when needed out of a pump up sprayer. That company also sells double eagle and groundskeeper which are both for concrete. The groundskeeper is like a light acid wash. Craig Harrison is the owner (frontline restoration) and he can be found on fb. He is happy to help people through problems. His products are available at powerwashstore.com
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