FAQ Search Select a Category BarkBath Cleaning Formulas Cleaning Tips Commercial Products Corporate Deep Cleaners Hard Floor Cleaners Mops, Brooms and Brushes Parts and Accessories Steam Sweepers Vacuums Warranty Web Site and/or go Is it ok to use BISSELL Formula that is left over from a previous BISSELL machine in my new BISSELL Deep Cleaner? What is the shelf life of left over formula? Answer: A good thumb of reference is if the bottle is "Unopened" the shelf life is around 18 - 24 months. If the formula is "open" it should be used within 12 months. Formulas that may be a little older than 2 years old doesn't necessarily mean it is expired. For best results, use the product within two years of the manufacturing date or within two years of the date of purchase. If the product is beyond two years from this date, the formula will still perform well; however, care should be taken to ensure the color of the formula is transparent and there is no objectionable odor.