Hmm... I wonder what is in the other 25%. I thought it was Xylene as it smells nearly the same. Usually when I go to buy a product like Goof Off I check the MSDS and sure enough most times it is a standard solvent that is re-packaged. Xylene works almost the same; and without the ethylbenzene which is nasty stuff.
Most lemon oils are just mineral oil with a lemon scent.