It's probably not needed, though, as the Spec Miatas don't have oil coolers and I've never heard of them complaining about it
Ignorance is bliss. We put a sending unit in the pan on our '95 when it was running ITS. Holy crap! Never saw less than 245-250. So we put in a modest size cooler and ducting, now it runs in the 240 range. Still sort of high, but not as bad.

My theory is that those cars are marginal for cooling, there is nothing extra in the system. Any disruption in the ducting, radiator degredation, having an air bubble etc will lead to problems. The oil cooler can't hurt.