When heating oil for frying, place a slice of raw white or yellow onion in the oil after you turn on the burner. When the onion starts to brown, the oil is at frying temperature. The minute you add something to the oil, the temperature drops so you may want to turn the heat up a bit to maintain a steady 375. Of course, a fry-oil thermometer works best, but the vessel you are using for frying may not be deep enough to allow you to use it.