Hey folks, I have just gone from a 2008 XL1200c to 2010 FXDC. I have always used Harley's 20W50 motoroil in the engine and primary/trans oil in the primary/trans. I see that a lot of people are going over to the synth oil. Harley's is a all in one oil. Is it good to change to the synth oil at the 500 mile oil change? How long is everybody going between oil changes on the synth oil? Would like all the advise I can get.