GTX 20w50 probably isn't what they are using....
Castrol – the oil lubrication company – is planning to build development and test facilities for datacenter immersion cooling technology at its UK HQ to support validation programs for its products, and customers. While many will associate Castrol with car engine oil, the company has now turned its thermal management nous to …
> Engine oil may have a lower thermal conductivity than water but as a coolant it has a lot of advantages.
True that. The low conductivity AND capacity hardly matters if you pump fast enough. Higher temperature helps a lot too. (Why we use Glycol in all water-cool engines, even in warm climes.)
Cars grew oil-pumps largely to carry heat out of bearings to allow more RPM and HP. Some WWII aircraft engines had massive oil cooling systems that did more than bearings. It has been said (citation needed, I know) that some Porsche engines were not so much air-cooled as oil-cooled; big air fins limit cylinder bore, more oil-cooling allowed an over-bore without major re-design.
And it won't freeze, and won't boil bad at engine temperatures. (Another bootnote: rapid-response interceptors in cold weather speeded warm-up by dumping gasoline/petrol into the oil to thin it so the engine could be spun to start and lessen oil-drag on the climb. When engine was full-hot the gas would boil out. It was hard on engines, but not fatal; not like the other side was trying to do to you. Since CPUs seem to have spurt-burst modes, this might come around again.)
"OVHcloud detailed how it has developed its own cooling technology using a mix of water and immersion systems."
Yeah, well, OVH might not want to use oil in datacentres which catch fire. :-)