oil life

I've tried searching for this, but came up empty so far. So I'm hoping someone here might have an idea. For years my 06 Tahoe Z71 4WD 5.3, would properly reset the oil life back to 100%. Now for the last 2 oil changes it has decided that it doesn't want to. On the previous reset attempt it...

So, i bought an 08 yukon in october and havent changed the oil. i have put about 7500 miles on mostly highway but the oil life remaining says 14% left. my question is do i change it every 3000 miles or when the oil life remaining gets to zero? im not shure what kind of oil is in it beings that i...