I decided to clean an old stock FC oil cooler I have sitting around to use on another car I have. I removed the large (1-1/8"?) bolt below where the lines meet the oil cooler. I never removed this before and to my surprise there was some kind of sprung by pass valve. I

Is this a type of bypass controlled by heat? Similar to the thermostat for the radiator. I've been building rotaries since 2004 an this is the 1st time I found this. I always thought it was a drain! It's always good when you learn something new.

Anyone here remove it?

 

Its an oil thermostat, leave it in there