1: the most commonly used is soybean oil or salad oil. The purpose of brushing soybean oil or salad oil is to accelerate the maturity, increase the color of the food and can reduce the loss of water in the food. It is used more often for seafood and fish.
2: spice oil, spice oil is generally used onions, ginger, peppers and spices extracted, this oil than soybean oil to increase the role of food flavor. Mostly used in roasted vegetables or soy products.
3: animal oil, usually with butter or sheep tail oil. This oil is mostly used in cattle and sheep ingredients, it is worth mentioning that some unscrupulous traders, with pork or other cheaper meat as beef and mutton sales, brush on this oil is generally not eaten not beef and mutton.4: red oil, generally with chili oil, but also with soybean paste squeeze, its purpose is to increase the color and spiciness of the food. There is a food additive called "chili oil" in the last few years popular in China's "crazy barbecue wings" in a large number of applications in the "perverted spicy" chicken wings.