I haven't heard about it, but I've heard some on-again-off-again strange whines out of mine. Only ridden it about 1200-1300 miles, though have had 1K service done in that time frame. I'm not familiar enough to know what I should and shouldn't be hearing.
I stopped using Syn3 in my trans after I seen metal shavings when I changed my oil I switched to Redline shock proof heavy.
I like the redline shockproof heavy, just for the reason it doesn't allow much metal to metal contact... The shockproof really works and on my old 2000 dyna, I put a set of rev-tech 6 speed gears(not the best) into that bike and rode hard with over 60,000 miles on that trany.... When I would drain the redline "never ever" did I have ANY metal on the magnetic drain plug.....
It quieted down a 09 road glide bike that a friend was going to take back to hd and demand a new trany cause his was so noisy... I sold him a quart of my redline and that made a believer out of him... His bike ran quiet and he was very happy with the bike....
The two quotes from the post here are from a user and one who might try some redline, it does quiet the 6 speeds down and they should last longer..
Just my opinion and about a zillion others who have tried it.
My 09 FLHR was noisy but not bad with formal+ in it when I bought it and the HD shop in bend oregon, Owner recommended to swap it out with redline shockproof heavy when I got it home.. Knowing I used it in my trade in...
Cascade Harley of Bend Oregon is where I bought my 09 bike and they USE and CARRY redline there.....
**Glider had a post that said;; (not a quote) That the hd 6 speeds were made using sub-standards parts and some plastic parts were use where metal would be better. Cheap if I remember his calling of them...
**Asked where he got that information he said(close) He just looked at the parts blow up of the 6 speed and could see them in use there..
**Hope you didn't mind me using "memory" Hope you chime in on that 6 speed information.
signed....BUBBIE