I've never had an oil analysis done on any car I've owned over the 43 years I've owned and operated cars but usually stick pretty close to manufacturer recommendations on the interval. I also still use 10w40 in all my cars. I ran an '88 Ford Escort 518K miles on various brands of 10w40 when the manufacturer recommended weight was 5w30. I just bought a '16 Versa about a year ago. When I bought it it had 10,546 miles. It currently has 20,1XX miles. I changed the oil shortly after buying it because I didn't have any idea when/if it had been done previously. When the oil was changed again at around 16K miles it had been in service for about 5,300 miles and the oil was a dark honey color on my fingers when it was drained. I thought to myself then that I thought the oil would be fine for 7,000-7,500. I'm running Citgo Supergard 10w40 that has been in my garage for probably close to 20 years in the Versa. I remember back in the day people spoke highly of the Citgo Supergard. Seeing Blackstone's recommendation on your Versa I may increase my OCI to 6,000 miles and see how the oil looks and feels. Nearly all my trips are long enough to heat the oil enough to burn off any moisture and most of my driving is very easy driving. My normal driving habits for the roads I drive are speeds in the 45-55 MPH range over 90% of the time