Without seeing the floor it is hard to be sure. It may well be trashed.
Where is the flooring; Kitchen, Warehouse, Workshop???
With any hard floor job I always try to establish flooring manufacturer and type. Then speak wth the manufacturer and devise best approach. Clarify / agree potential issues with customer before doing anything.
Glue; if this was water based then you'd have already seen at least some improvement using a green pad. I would expect therefore that you'll need to try a solvent based cleaner. You may also benefit from the use of steam.
What type of oil?