Which foods are kosher for Pesach with only a "year-round" hechsher, or with no hechsher at all?
Extra Virgin olive oil. Source
All extra virgin olive oils are Kosher for Passover, as long as it bears the OU symbol
All other oils (including olive oil) require a reliable Kosher for Passover certification to be consumed on Passover.
Milk contains added vitamins that contain a slight chometz risk. Therefore it is best to purchase milk before Passover at which time chometz can be nullified (batel).
Regular Ground Coffee Source
All regular ground coffees are acceptable for Passover use when bearing an OU.
Coffee is often decaffeinated by means of ethyl acetate, which is derived from either kitniyot or chometz. Therefore, decaffeinated coffees are not acceptable for Passover unless specifically listed in the section of the Passover guide which contains items that to not require Passover certification.
Instant coffees often contain maltodextrin, which is derived from either corn (kitniyot) or wheat (chometz). Therefore, all instant coffees require special Passover certification unless explicitly mentioned in the section of the Passover guide which contains items that to not require Passover certification.
Salt that is iodized by means of a corn derivative is (kitniyos) and therefore iodized salt requires Passover certification. Un-iodized salt does not require Passover certification, nor does sea salt.