Heating an oil changes its characteristics. Some oils that are healthy at room temperature can become unhealthy when heated above certain temperatures. When choosing a cooking oil, it is therefore important to note the oil's heat tolerance, and to match the oil to its use in cooking.If you produce waste cooking oil as part of your catering business, (for example as a chip shop or other takeaway outlet or restaurant), then you must ensure that it is stored properly, that none is allowed to spill and that it is collected by an authorised collector who will take your waste to an authorised site for recovery or disposal.Waste cooking oil must not be poured down drains or sewers because this inevitably leads to blockages and odour or vermin problems and may also pollute watercourses leading to problems for wildlife. Such action could also result in potential prosecution. Nor should waste cooking oil be disposed of with the rest of the catering or kitchen waste because it may cause spillages leading to odour or pollution problems or waste contractors may refuse to remove it.