Stontex Oil Remover works amazingly well.
This is a very popular and effective oil remover, however if the patio/material is not sealed and very porous then oil especially hydrochloric/ motor oil can penetrate very deep into the material.I would suggest apply neat onto the stain then agitate vigorously with a nylon brush allow to dwell fo about 20mins then use warm / hot water mixed with some household detergent to flush the cleaner out of the material this will remove the oil stain also.
You should see an improvement each time however if your stain is too deep then we can suggest engaging one of our local Stonedoctors using commercial grade chemicals and an industrial steam cleaner should solve it.
NB this type of situation is why we advocate so strongly that paving should be sealed with a proper high grade Stontex sealer as stains would be much easier to remove if this was the case.