I had a clean floor to start with. I did my garage/workshop area with
the epoxy stuff. One kit per single car garage size. Other than a
couple of spots where the tires have scuffed the stuff away (my fault
for not letting it likely cure completely), it is great. With the
smooth surface, it sweeps or hoses down nicely. There is an acid etch
with the kit that should clean things up pretty good. If there is a
lot of grease, all bets are off. About $65 for each kit. I have had it
in 18 months now. You sprinkle "speckles" on it, which breaks up any
irregularities in the concrete. It does have to be warm ( 60f) to use
the stuff, however, if that is an issue. Takes a couple of days to set
up/cure.