Join Date: Dec 2011
Location: Dayton, Ohio
Car Year: 2012
Car Model: XT Touring
Feedback Score: 1 reviews
Just for the record, the thing you're referring to is more of an oil heater than a cooler. It helps the oil warm up quickly.
Regardless, it's unlikely to be leaking between the disks. I would replace the o-ring again, be sure all the surfaces were clean, etc. Be sure it's torqued correctly. There may be a better way to seal this whole assembly to the block - maybe coat the o-ring in sealant or the lips in form-a-gasket. Someone else please jump in on that.
You did not indicate how much oil is leaking. Is it is little - a few drips? Or is the garage floor flooded? If it's a few drips, that's a Subaru "feature".