Heat should result in some oil circulation - fans might help but I don't think they'll be a must. It's a great thing when you want to chill all these coils without noise.
If this PSU was exposed to high load, it would produce pretty much heat. Some kind of heatsink might help - like bidirectional - one part in oil, one on air.
Great idea. Perhaps they'll start making such passive PSUs. Were there any problems that are worth reporting? Personally I'm interested in "copying" this idea...
Could you perform some long-term tests and tell temperature difference - PSU <=> ambient and how much power computer used?
Your mod is unique as it's PSU only. Cooling entire computer with oil is a bit difficult, when computer is "high performance, high power". You simply get better results with WC as it's got more effective blocks and you need to chill oil somehow as it will be warmer and warmer without some kind of radiator. WC on critical parts + oil on rest + secured disks might look interesting tho.
Modding whole computer to mineral isn't that great sometimes and requires a lot of effort. PSU-only oil mod on the other hand looks very practical, much easier and maybe even worth suggesting for overclockers who look for silence.
Very inspiring, thanks for input and welcome to the forums.