I have changed hoses ,radiator,thermostat I now have a leak at the rear of thermostat housing ,it looks like the littl pipe coming out of the thermostat housing what is this pipe? Or could it be the housing just not tightened up enough? It’s a 2002 wrx bug eye wagon

 

Not the front crossover pipe?

 

Apparently it’s the oil cooler pipe? Little 90degree pipe ordered a couple but looks a pig to replace?