Hello, I just hit 1500 miles since buying a new to me 2020 Subaru Impreza with 48k miles, I believe the previous owner was doing extended oci because after only 1500 miles the new oil I put in is already black, on my 2017 Outback and 2004 Forester the oil is clean even after 5k miles, would flushing out the current oil and maybe using an engine flush be a good idea?