You might consider the fact that the oil was far less viscous at the temp the engine was running at, which is why it would work well.
It could be done in a comp, but you'd have to compensate for the viscosity with a good pump, and that's either going to add a lot of pump heat, or cost too much.
Pumping a viscous liquid from a mag drive probably isn't the best idea, so you're looking at another type of pump, which will be noisier.
Also, using water, it's relatively easy to get a lot of turbulence, which improves cooling a lot. With an oil, achieving turbulence may be unpractical.
I think you should try it. You'll have to obtain the viscosity figure of the oil, and spec a pump that can accept that liquid.
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