My 2008 wing has the same 8000 mile oil change schedule, but over the past 10 years i’ve noticed that beyond 6,000 miles the shifting doesn’t feel as smooth, so i try to change it every 6000 miles or so. It’s usually pretty dirty when it comes out so I don’t feel bad about doing it early. Never had the oil analyzed so no idea what the chemistry is....but oil isn’t expensive, so i just change it.