While I was riding today I noticed that the motor on my 2001 Fatboy was making more noise than usual. Im wondering if the summer heat is to blame for it. I am running HD 20w50 conventional and its about 85-90 degrees and very humid where I am. I changed the oil about 4-5 months ago and have put on a little over 2,000 miles. I know that when oil gets hot it thins, so if that is the reason for the noise, is there a better oil to run to get rid of the noise and in turn, better protect my motor?