[RWebb]

my 2010 Forester does the same thing (and I also don't know how long it can go (tho I do know it will go somewhere else as soon as I can get a new SUV))

I think the risk varies with the arrangement of the cooling and oil ports, but don't know what the layout is on mine much less your sisters

one thing you can do is to check and see if it is covered by one of the many class action lawsuits that has been won against Subaru (mine isn't and I know some vehicle older than mine are covered)

on mine a fix costs about $2,000 which is about 25% of the value of the vehicle...

Good Luck!