Composting vegetable oil.

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.

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.

I think the oil would break down eventually, but question what you would gain by adding it to compost.  Looking at nutrition content on the label of a bottle of vegetable oil, there is some carbon in it, but no protein (therefore no nitrogen), no potassium. I can't comment on phosphorous, not on the label. Decomposition requires a certain carbon-to-nitrogen ratio, too much carbon relative to nitrogen will slow decompositon.