Can I compost...
Cooking oil?
No.
No, most of the time anyway.
Cooking oil should be avoided in case it attracts rodents or other undesireable creatures to your compost heap. It also can displace water in a small compost heap and thus slow down the composting process.
However, vegetable oils such as vegetable oil itself or olive oil can be composted in very small quantities as long as they haven't come into contact with any forbidden food stuffs (like meat, cheese or fish). Mix in well with 'brown' matter such as cardboard or straw and turn regularly to keep it aerated. If you can't manage that, it's probably best to avoid it.
Large quantities of used vegetable oil can be recycled - your local council should be able to advise if it is possible in your area.
Small quantities of cooking oil that's been mixed with other fats and is solid at room temperature can be reused to make bird feeders for the garden.
In category Leftover food