[CydeWeys]

I doubt there's any component in a PC getting remotely close to the ignition point of oil (which for canola is 424°C). Plus, it's going to be a minimal amount of oil.

I'm more worried that the oil won't get to a high enough temperature and thus won't polymerize, so it'll flow out and ruin some other component, or go rancid, or something. Thermal paste won't move on you. Oil will.

[zhengyi13]

Oil will certainly move on you, but it might not destroy your components, depending perhaps on the specific oil chosen: you can actually buy or build fully oil-cooled PCs.

https://www.pugetsystems.com/submerged.php as an example.

[ponker]

That's mineral oil, not cooking oil. Mineral oil doesn't go rancid.

[Scoundreller]

Presumably there’s enough surface tension from both sides to hold it between the gaps and resist gravity (if it’s a vertical CPU).

Pretty much any Solid-liquid-solid or solid-solid-solid interface will be better than solid-roomTemp&Pressure gas-solid.

The whole point is to conduct heat better than air, and most things will.