I have a '01 Lincoln Continental and the driver's seat is getting pretty tired and dirty looking. I have tried Mequires Leather Cleaner and also Leather CPR as suggested by another post, but neither product are removing hardly any of the grime when used as directed. I let the product sit on the seat for several minutes before removing with a clean cloth. Is there a more "aggressive" product that I can use that might give me better results? Thanks for any advice you can offer.