Chris,
I would do a 3 step clean on this,
Resiblock OR first see how much has come out, then OT8 as a follow up clean, this can go on wet/damp surfaces so pretty much straight away after the OR. I'd follow that up with an Hydrofluoric acid wash, safe on Granite, but good quality PPE is very much needed as this is a nasty one to use.
I have used this on Granite before and it will flatten out the surface so might well rid any remaining oil staining. Tensid do the acid, and will send you a sample.
Poultices would be an expensive option and time consuming to do.
