Koyo Radiator vs Oil Cooler
 

How much is one better over the other? I appreciate that an oil cooler would (probably) be better at keeping the oil cool but would an after market radiator be better at keeping the engine and oil cool? I ask because it is my opinion that an aftermarket radiator is more elegant. That is, there are no additional hoses/pipes in the engine bay but I suspect that an oil cooler would be more beneficial.

Sorry, I'm not directly answering your question.
But if you were to install a vented hood, airflow through the radiator and around the (oil-filled) motor block should also be improved:
http://body-kitz.com/contents/en-us/...by_Seibon.html

(Some cars also had vented hoods in stock configuration:
http://www.classicscars.com/rally/205t16new/car1.jpg )

Thanks rx3 for your reply. I have considered this but I would have to get the original hood modified as a carbon fibre hood is not street legal here.

Oil temps on this car rise really quickly (above 100 degrees easy) even on street spirited driving while coolant seems to hold a constant 92 degrees Celsius (obtained from data on this forum). Personally I'd address the oil cooling first because oil contacts all critical engine components directly and can transfer heat from them much more efficiently. Also since this car takes 0W20 which isn't exactly thick, it would be good insurance to keep the oil from thinning too much from heat.

With an oil cooler, you will need more oil for oil changes and when it does get changed, the oil in the cooler and lines don't actually drain. just something to consider.

With that being said, the radiator probably isn't the bottleneck of the cars cooling abilities

I switched to 0W-40 (Motul 300V) for this reason.

A lot of people overlook a GOOD oil at helping keep oil temps in check and stable.

These cars get really hot, really fast. Add in forced induction and even more so. Sometimes I feel like I am dealing with a rotary.

I doubt this engine will EVER be as temperamental as a rotary.

what would you consider to be a good oil? any recommendations?

I was almost 100% set on going with an oil cooler first, but if a bigger radiator like the Koyo can give similar results like an oil cooler I rather go that route. Can anyone else give an explanation between the two?

For the price of a good oil cooler (Perrin) vs radiator (Koyo), it's about half the price for the radiator.

I went with a radiator first. My thinking is if the coolant cools faster, and more, it'll help cool the engine better, in turn helping keep the oil a little cooler. I have no empirical data to back this up, just my opinion. Also, I have a vented CF hood to help the hot air escape better.

I've ordered the Perrin oil cooler. From what I have read water temperatures don't get nearly as bad as oil temps. Ah well, everything's a compromise except for those things that aren't.

What I don't understand is why the oil cooler kits cost 2x as much as a big ass aluminum radiator from Koyo...

Not convincing anyone, but I'll be going w oil cooler first over aftermarket radiator... but that's just me.

Oil Cooler first for me. Same logic as many above.