Originally Posted by Elmer
Sorry to ask, maybe a silly question, but why do you think it has something to do with the HG's? The last time I replaced the oil, I haven't spotted any coolant in it. The coolant itself is very clear as well, nice green color without any whitish/oily substance. The fluid around the radiator cap is rusty but as it is very local I guess this is due to the cap itself.
Typical Subaru head gasket failure isn't coolant mixing into the oil. Its the combustion gasses seeping past the head gasket into the water jackets around the cylinders. There is a layer of teflon on the gaskets that eats away over time and causes the leaking.
I've never seen a Subaru blow a head gasket in a way that it gets coolant in the oil like most other cars do.