Can I still use the Obagi Nu-Derm Fx System post expiration date?

There have been several studies looking at whether it is safe to use products past their expiration dates. They have all shown that it is safe to go past the date somewhat. None, however, exactly define how far after the expiration date is safe. There is no data that I am aware of regarding the Obagi Nu-Derm System. The result of these studies, therefore, mean that it is probably safe to use the products a short time past the expiration date but you should not stretch the time and absolutely should not use any of the products if they do not look like new products.