I completely agree. This is why I said it doesn't add up.Ummm...exactly where are solenoids in the oiling system of the Subaru? Engine flush recommendation by dealer = BS PERIOD. There is NO WAY, NO HOW that you could sludge up an engine in 6,000 miles. You were lied to plain and simple to extract your hard earned money from your wallet.
Interesting, without seeing the car it's hard to say but I agree sludge could be an issue. I'd start checking my oil more often and look more closely at driving habits. If all that checks out I'd make sure the dealer was actually changing the oil.As requested, trouble code was p0028