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Used oil being poured into a bottle

How to recycle used oil

Extra Life Oil

The importance of recycling used oil

In Spain, nearly 350 million liters (92 million gallons) of used cooking oil are generated each year: 10 liters per person; around 72% is recovered in the hospitality industry, yet the figure barely reaches 5% in households.

Recycling used oil has many benefits: it allows for the production of renewable fuels and reduces the need to extract new raw materials, among others. Do you want to know how to recycle it correctly? Here are some tips and guidelines.

In the past, used oil was mainly used in households to make homemade soap. However, due to the time required and the difficulty involved in this practice, it's not as common as it used to be, so the oil is discarded more often. This, in addition to the fact that it's known that there are other uses that help make the most of this waste, highlights the importance of recycling it correctly.

Improving these figures and percentages is precisely the purpose of Spanish Law 7/2022 on waste and contaminated soils for a circular economy, under which local governments must implement specific collection systems for usable waste by 2025 (including oil).

Why is recycling important?

Used oil being poured into a bottle

Used oil is a waste product that can cause significant damage to the environment if disposed of incorrectly (e.g., by flushing it down the sink or toilet). A single liter of oil can contaminate 1,000 liters of water, according to data from the Aquae Foundation. Also, when it is dumped into the sewage system, it causes major blockages in pipes and sewage treatment plants. This makes the treatment of this water slower and more costly and requires high energy consumption.

The amount spent on unclogging blockages due to oil and grease flushed down drains amounts to more than €90 million per year in Europe alone.

Therefore, in addition to the energy and economic savings it entails, recycling used oil is an example of circular economy. 

Used oil in a bottle and a funnel

There's a wide range of benefits that come with recycling this waste: 

  • Reduces pollution and waste: By giving it a second life, its uncontrolled dumping is minimized, including the amount of waste that reaches the environment.
  • It's used to develop renewable fuels that aid in decarbonizing transportation, whose main goal is to cut carbon emissions.
  • Promotes employment: The versatility of this waste enables it to be transformed into high-demand products such as renewable fuels, asphalt materials, or fertilizers, which translates into job creation. Implementing oil collection and recycling systems also means that workers are needed in areas such as collection, treatment, and transportation of this waste.

How to recycle used oil

Correctly recycling used oil is vital for extending its useful life. Therefore, following these steps is recommended to make the most of this waste's potential:
 
  • Store correctly: Pour used oil (also from canned products) into empty plastic bottles or other specific containers once it's cold. Make sure there are no leaks or spills, and if there are any, clean the container with paper towels.

  • Bring to collection site: Increasingly more towns have specific containers for collecting used oil. Alternatively, at waste facilities, some NGOs and waste management companies will usually take care of it.
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Uses for used vegetable oil

Nowadays, used oil can have a highly profitable useful life and can be used for different purposes. These include the production of fuels of 100% renewable origin, which help make the most of this resource.

Nonetheless, its versatility actually goes far beyond that. It can also be used to manufacture surfactants –the basis for many everyday products like detergent, cosmetic creams, paint, and varnishes– as well as candles, fertilizers, among others. Therefore, it's a waste product that retains its value beyond its first use.

A person pouring oil on a frying pan

Recycled oil as a raw material for fuels of 100% renewable origin

Using recycled oil to produce renewable fuels —mainly biodiesel— represents an opportunity to promote the circular economy and the decarbonization of transportation.

Biodiesel is a renewable fuel whose CO2, SO2, and CO emissions are lower compared to other fuels. In fact, the U.S. Environmental Protection Agency (EPA) estimates that CO2 emissions are 80% to 90% lower in comparison to conventional fuels. Moreover, they don't contain sulfur, which prevents this gas from being released into the atmosphere, and they are used in conventional diesel engines without requiring any modifications.

Repsol with the collection of used oils

A woman recycling a used cooking oil bottle

At Repsol, we have made over 650 service stations in the Community of Madrid, Galicia, Castila-La Mancha, Castilla y León, and Aragón available to users who wish to dispose of their used oil. Additionally, for every liter of oil collected, users will get €0.30 added to their Waylet app balance.

Repsol has also launched in Cartagena the iberian peninsula's first plant for the large-scale production of fuels of 100% renewable origin, on whose construction and launch worked 1,000 people. 300,000 tonnes of waste will arrive at it every year —mainly cooking oils— to make fuels of 100% renewable origin.

Updated as of October 2025.