I have not been a regular customer of Blackstone Labs for oil testing but I did get the oil tested for this milestone. I entered on the form that I added .5 quarts of oil between changes. I have since found where some of that oil has been going. I have a leaking output shaft seal (drive shaft out of the engine) and a leaking shifter shaft seal. They have probably been leaking for a many miles but within the last 4000 miles they have become worse as in gunk on the back of the engine. I have new parts ready to install.
I'm not trying to brag (much) here but I can only agree with Honda's oil change interval of 8,000 miles using regular oil. My 10,000 mile interval with synthetic has not hurt the engine at all. I think if a guy could stick with it this engine could easily surpass 500K. To recap I have used nothing but Rotella T6 usually 15W-40 but a few times 5W-40 when the 15W was not available and only the best of the Walmart Supertech oil filters (#6607) both changed every 10,000 miles.
I do only ride like a "little old lady who only drives it to the store and church on Sundays".