Just changed to synthetic on my 94 Heritage. Put on about 170 mi today no signs of any leaks and bike seems to really like it. Amsoil in engine, Spectro GL1 in tranny and stayed wit HD formula + in primary. Could be my imagination but seems like bike liked to go from 4th to 5th around 58-60 mph but with new fluids dosent seem to need the shift till 65 mph. Very smooth now as well. Glad I did it.