FRUIT: Abura Abura no Mi (Oil)
Not to be confused with Seki Seki no Mi (Oil) which is gasoline – that's a separate chapter altogether.
To be clear, oils are defined as substances that are liquids at ambient temperatures and do not mix with water, but may mix with other oils and organic solvents. They have a high carbon and hydrogen content and are usually flammable and slippery. This general definition includes organic oils which are produced by living organisms and mineral oils meaning crude oil, or petroleum.
In this case, however, we are leaving crude oil (petroleum) as a separate fruit.
Quick overview, we get some ideas of application:
1. Adhesion – on both fronts, since while most oils are by nature slippery, some do adhere. Seeing as how the user can cover their body or anything they touch – hands or feet – then the user has a rather unique battle tactic at their disposal.
2. Manipulate properties of oils – within reason I am assuming
3. Napalm generation – some oils can be made explosive, especially since they are already highly flammable and consist only of carbon and hydrogen as a rule
4. Oil generation – a must for oil attacks
5. Poison Generation – kerosene a good example
6. Scald Generation – superheated oil is not the same as oil on fire (an excellent tactic for the user to use)
7. Oil Armor – can be either suited for attacks to slip off or a hardened version
8. Oil Giant – possibly an Awakened technique, but still a decent possibility
The user would definitely need to have a source of fire on hand, but otherwise, the user is – by estimate – immune to most bladed weapons due to his oil armor.
By the same design, the speeds created by user sliding on the floor (oily feet) makes the user very suited for blunt weapons.
That's my opinion, however, but still a possibility.