Gary,
First ask if the customer has tried to clean it themselves (of course they may not admit it). Then take a clean cloth and dab with the dry solvent to get an idea if it’s going to budge. If nothing, I would leave it alone. If it does then great. If you have a large spot, you can squirt the dry solvent directly on but be ready to flush using the uph. mate. I do several car dealerships that track grease and oil from the service dept and we go around and spot clean the grease spots with solvent using a cloth, then apply FAE and buff with good results. I have found that the solvent doesn’t leave an oily residue like TGP, etc. and gets most oil and grease stains out. If the spot is large or there’s a concrete slab underneath the carpet it may come back but it will most likely be much smaller and may need 1 more extraction. The dry solvent has worked well for me with tar and grease, it is one of the Heaven’s Best lifesavers. Also make sure you work these extras into you original pricing. Good Luck.