[Odders]

Has anyone done it?
I've just emptied the fryer & there's best part of 3 litres of old oil & I was thinking of adding a bit each time I put in a decent amount of composting material.
A search on Google brings up the usual mix between 'yeah it's fine' & 'aargh no, you'll destroy the planet!!!' & everything in between but zero empirical evidence or scientific studies that I can see.
It'd be no more than 6 litres annually & split across probably two fills of a 1.7m³ bay & three of a 0.8m³ bay, so not exactly drowning my material in oil.

[wolveryeti]

I wouldnt do it personally - will just degrade oxygen permeability of your heap so it will break down slower. Oils are also basically long chain hydrocarbons so not clear what you are breaking down for the plant that it cant synthesise itself....

[missmoneypenny]

I can’t see that working. Surely it will create a water proof barrier between the vegetable matter and decomposers, and slow down the composting process. Not to mention the mess. I take mine to my recycling centre, they collect cooking oil.