i use regular castrol bike oil in both wings. if i remember right my 1500 calls for an oil change every 8000 miles and doesen't say to use or not to use synthetic. i change oil and filter between 4000 and 5000 miles
99% of use is considered Severe Service so your 4000 oil change interval is correct.i use regular castrol bike oil in both wings. if i remember right my 1500 calls for an oil change every 8000 miles and doesen't say to use or not to use synthetic. i change oil and filter between 4000 and 5000 miles