I have a 1800cc, dohc, turbo engine that I just rebuilt. Yea, GTX, or BP 26 with a vj20. After the rebuild, I noticed the oil turn black really fast.
Black means carbon, right? This is conventional oil.
oil break down, soot/ash, and detergents doing its work
black does not directly mean the oil is bad... to determine this, an oil analysis needs to be done
expect the oil to get dirty fast on a fresh engine after a rebuild