If this is my car and I have some vacation time, I would tear it apart and perform a thorough inspection to see what's at fault.
Bu then again, this isn't my car and people come post here typically looking for easy way out. Things like (ring fix in a can, smoke free, motor-hunny are big sellers for people just don't seem to care or too ignorant to understand the economics behind it).
Yeah, as a car owner, one may argue the economics of feeding an oil burner car with 1 qt every 300miles would be an "economic" thing to do but they typically tend to disregard the impact to other things surrounding them. Things like environment pollution, etc. At the end of all these, it would just come back and sting us.
Yes, I know there are some less-than-fortunate people who need to make the most out of their vehicle and I understand/forgive them. Truth is, people shall be penalised for not properly maintaing their vehicle the day the purchased it. And manufacturers of inferior quality products shall also be penalised for dumping "garbage" into the market with unacceptable service life for the sake of "planned obsolescence".
Well, enough personal ranting already. Back to lurking/invisible mode I go...
Q.