[ZeGermanHam]

Originally Posted by steve25

I had just such a leak in my daily driver Subaru.
It was a head gasket and a very very small leak into a cylinder.

My coolant over the course of 5 days of a 74 mile round trip to work and back would go down by a little over 1/4 of a gallon, just enough to use up the reserve in my overflow tank.

It never steamed or smelled out the tail pipe either atleast at hot idle.

I got lucky and 3/4s of a tube of the Brass and Aluminum powder fixed it.

Subaru head gasket failure every 100k miles seems to be the rule rather than the exception, which has been my experience with my Impreza. That said, I would never recommend using the mechanic-in-a-can sealants. They do a number on the coolant passages, radiator, and the heater core. And yes, I know Subaru dealers used it.