OEM oil cooler
 

Im in the market for an oil cooler for my nissan. I have my eyes on an FC cooler as the dimensions work well for my setup. I have been informed they have a thermostat located in an end tank. Are the thermos any good or do they become a restriction when the cooler needs to flow full bore due to rising oil temps? I would like to weld -10 AN fittings on the end tanks but am concerned the thermostat will become damaged. At what temperature does the thermostat open?

The thermostat bypasses the cooler at low temps, giving the oil a path of least resistance around the cooler, rather than the other way around, so it doesn't cause a restriction at higher temps. It can be disabled though if you really want.

It is a 150F thermostat. the factory threads on the oil cooler are M16 so you could use a banjo bolt or buy adapters if you needed to.

https://www.rx7club.com/attachment.p...1&d=1278862241

https://www.rx7club.com/attachment.p...6&d=1274354477

look at the diagram of the right end tank. it shows the oil cooler thermostat. You will have zero problems with this oil cooler if you install it correctly with reliable oil lines. They're very well built and they do a good job of cooling. It is basically the best oil cooler Mazda ever put on a rotary.