All regular harley's take 20w50 motor oil, regular or synthetic is your choice.
Yes, you can even mix them.
yes
No, you can even mix synthetic with conventional oil. It will do no harm at all.
No it is fine to switch back to regular oil.
20/50 SYNTHETIC OR REGULAR MOTOR OIL............ CHUCK MC
yes, if the car manufacturer dictates that regular oil is acceptable. If your car requires synthetic oil as dictated by your owner's manual, then DO NOT use regular oil. May void warranties if your car is still covered.
If you have kept regular oil changes, no prep is required. Just go and put the synthetic oil in.
Harley recommends their own Syn3 synthetic oil or their regular H-D brand 25W50 fossil oil (both made by Citgo), but I use & recommend Mobil One 15W50.
yes it is fine but of course synthetic is the best to use if you can. Double check your oil requirements with your owner's manual. If it states that normal oil is okay, then go ahead. If your owner's manual dictates Synthetics, then DO NOT switch.
its the same process as changing synthetic oil, except you use regular oil.
20-50 synthetic