I am about 7,000 miles into a fresh rebuild and im using fully synthetic mobil 1. I do not burn any oil what so ever, and have used synthetic from the start (despite contrary opinions to this). My question to you guys is, those who have used synthetic and regular oil in the vehicles, do you notice that the synthetic seems to get a bit darker, faster? After about 1500 miles, it seems my oil is pretty darn dark. And my block was totally cleaned out, and all parts were cleaned. I change it ALWAYS before the 3k mark. Just wondering if this is normal from synthetic oil, and why it would be doing this. Thanks.