You don't want to mess with the guessing. It states keep in a cool dry place for a reason. I would be afraid. You never know, especially with infants. It's best to err on the side of caution. I can understand the asking, it's so ridiculously expensive . I would call the 800 # on the can .if you are undecided. they are very helpful. my guess is they tell you to toss it
It is not safe to use powdered infant formula that has been left in a car for 4 days. Infant powdered formula should be kept in a cool, dry place at all times. Leaving powdered infant formula in extreme temperatures (as can happen when it is left in a car for a while) can affect the formula's quality.