Cooking in a deep fryer is a fun way to add a whole new dimension to food. It changes the texture of the outside surface usually to a crisp coating, not attainable by other means of cooking. It also tends to be a much faster form of cooking since the temperature is much hotter than boiling and the oil is in direct contact with the food, unlike baking.
Different Grades of Oil
One of the most important parts of frying with oil is knowing what kind of oil you are working with when you fry. Different oils will break down at a molecular level depending on their chemical structure. The oils that break down at the lower temperatures are usually not suitable for frying. Oil like coconut can withstand the highest temperature without oxidative damage while olive oil is probably the most unstable. Frying oil should never be used again if it is brought to the point of smoking.
If you read recipes for deep frying, almost all of them recommend the oil to be within the 350 to 375 degree F range. At this temperature, the moisture within the food actually repels the oil keeping the food from becoming greasy. Strive to heat your oil to 375 before the food goes in and then don't overcrowd the pan. The temperature will drop with the addition of the cooler items, but will climb back up after a few minutes.
There is a big difference between cooking a turkey in a deep fryer and cooking french fries. Something as large as a turkey will take much longer to cook and if cooked at the high temperature range, will burn on the outside before the inside has reached a proper temperature. Turkeys need to be dropped into hot oil of about 375 degrees since the temperature will then drop. Hold the heat at about 325 to 350 degrees to ensure it doesn't burn.