What is the ruling on exchanging used oil for new, clean oil and laundry detergent?

Cooking oil is subject to usury (riba) because it is measured by volume and is edible. If oil is exchanged for oil:

1. If they are of the same type (e.g., corn oil for corn oil), then equality in quantity and immediate possession at the transaction مجلس (gathering) are required, regardless of quality. 2. If they are of different types (e.g., corn oil for wheat oil), then only immediate possession at the transaction مجلس is required, and a difference in quantity is permissible.

Oils take the ruling of their origins; for instance, corn oil takes the ruling of corn, and olive oil takes the ruling of olives. It is not permissible to add anything else to one of the exchanged oils if they are of the same type, due to the lack of equality.

Used oil is not considered real food after it has been heated, and therefore, it is not considered a usurious commodity according to those who hold that the underlying reason (illah) for riba is measurement by volume and edibility. However, according to the view that the illah for riba is measurement by volume only, then usury applies to it.

The safer approach is to sell the old oil for money, and then use that money to purchase new oil or whatever is desired, in order to avoid riba and doubts.

It is imperative to ensure that no harm or deception occurs from this exchange, and that it is conducted under the supervision of an accredited regulatory body, given the danger of reselling old oil after treatment as if it were new.