Have just found out that the valve seals on my bike need to be replaced (9500 miles). Have been using about 1 qt of Syn3 every 2000 miles. By checking the plugs myself is how I found this issue. Checked my service records and the plugs were replaced at 5K. Supposed to be good till 10K. Recently had some severe hesitation on acceleration-what caused me to check the plugs, install new - checked one week later and they looked almost as bad as the others. Got a sense that the dealer had dealt with this before but they wouldn´t say. HD is covering replacement costs except for a $100 \