I just received my blackstone labs UOA kit for my 2008 silverado (6.0 V8) which I tow VERY hard with, and just plain drive hard...and I have also altered with an aftermarket computer tuner, and I am contemplating running a UOA now with almost 4,000 miles, and 50% oil life left on the OLM on pennzoil platinum 5w30 since the 3,000 mile mark, and short drain intervals due to break-in wear.....should I push this oil farther?? This last fill was this year with 26,911 miles on her, and I now have 30820. I am not gonna be sampling every oil change due to money issues,....I just want to know roughly how long I can run this oil? I dont want copper issues, and these engines have copper issues during break-in. Should I keep going?? ...or sample now??