I think if HD calls for 5000 miles on regular oil it should be no problem going 5000 on syn. I feel if you are going to change at 2500 regular oil should certainly hold up with out issue.

 

5k engine (Syn3 or M1-VT) & primary (Formula+) and every 2 years transmission (Redline Shockproof Heavy.)

 

For me it's- motor Mobil 1 VT 5000 miles -primary HD dino 5000 miles - trans 85-140 Mobil 1 20,000 miles.

 

Every 2500 as most