A couple things that they didn't put in the comment section are that I used 5 qrts of M1 0w40 and 1.5 qrts of M1 5w30 HM that I had left over and that I had this oil was in for 14 months. It was replaced with M1 0w40 only.
Great wear #'s - M1 0W-40 is tough to beat. I'd run a longer OCI - 7-8000 should be easy. Drop a Bars Leaks tab or two in the radiator to solve your minor leak. Those tabs are available at any GM parts counter or at Nappa auto parts.
I only drive about 5000 miles per year so I figure a once a year oil change is best. Not worried about getting top miles out of the oil. I do a tire rotation at 5000, too, so I keep those two maintenance items together for simplicity's sake. I've even matched those intervals to my odometer!
Hence the 65K change (well, close...the next WILL be at 70k).
Update on Mobil1 0w40. I forgot to tell Blackstone I used a little bit of a stop leak product. Either this did it or somehow the previous sample had some contamination...don't know. At 2500 miles, I think it could go to the 5000 I usually do.