Don't you hate it when you think you're done, but the garage floor wont come clean?! I have been using the Rustoleum Epoxy kit with the 2-stage Epoxy, etching, and sprinkles.
- Extensive spraying with hose and dawn (The stuff labeled as grease-cutting) let set approx 1 hour
- Pressure washer (Cleaned up some of the darkness but the stains are still there)
- Boxes and boxes of powdered Tide
- Zep Industrial Purple Degreaser from Home Depot
- Black Magic priest attempted to remove the curse from my garage by praying the stains away
Cleaning concrete with degreaser/detergent usually only works for fresh stains and grime. If it has set in at all, it's time to go to acid.
Go to your favorite home improvement place or, better yet, find a local concrete products store (the guys that sell stuff like concrete stains, stamps, etc.) and tell them you need to acid wash your garage floor. There are various ways/products to do this. You could also get some muriatic acid from a pool supply store and DIY.
You must dilute it.
Don't go dumping it on the floor before doing research. The pool guys might even have some tips on ratios/equipment, as acid washing is common thing for restoring concrete pools. Keep that pressure washer handy as you'll need it for neutralizing/rinsing the floor, and take all reasonable safety precautions (nitrile gloves, eye protection, etc.) because, ya know, it's fucking muriatic acid.
After much scrubbing, tide, scrubbing, and more scrubbing, the floor was clean enough to put down a nice coat of primer and start rolling on the epoxy. Thank you for all your suggestions, I would have still been attempting to clean it right now.
If all else fails you can always paint your floor. I know its not exactly cleaning it, but it would def look better and you can pick a color that compliments your vehicle