I have a 2007 Street glide with about 35,000 miles I purchased in April of this year. I put about 3-4k on it this season. I recently changed the oil in all 3 holes from whatever was in it to Mobile 1 V-Twin in the engine and Mobile 1 gear oil in the primary and transmission (75-140 in one and 75-90 in the other...I don't have my notes on which one went were handy, but I used this site to determine it at the time).

At some point after changing the primary fluid I started noticing a squealing noise in the primary. I noticed this one day when the radio was off (I normally run the radio pretty loud) so I'm not sure if the noise was there before or not.

Given info provided, what are the likely culprits/fixes?

1) try changing back to HD primary fluid?
2) Maybe primary chain tensioner issues?
3) Some kind of inner primary bearing problem (or is that only 2006 Dynas that have this problem?)
4) something else?

 

Gear oil is the wrong fluid to use in the primary. Switch back to HD primary fluid. Run it a couple hundred miles and change again. It would be even better if you pulled the primary and got all 45 oz out on the first change. Then see how it sounds.