Ex @78k miles : My oil is black by 1000- miles after a filter/oil change. Should I try a flush e.g. Seafoam etc ?

 

Your oil will get black, that is just natural, especially after 1000 miles. if it turned black after 100 or something then you may be burning oil, but if you aren't losing alot of oil then I wouldn't worry about it.

 

Somewhat normal. Likely a little above-average blowby is causing this, due to worn rings.

 

It can also be caused by driving short distance trips frequently. If the car was poorly maintained since it was new and sludge built up in the motor, that could also cause it and seafoam would help. If the rings are worn, and blow-by increased that would also turn the oil black quicker as well.