[JoeSixPack1]

Engine harmonics!!! 2nd only to heat as an engine killer!

I started using the synthetic HD oil, 3 oil changes back and noticed the top end noise increased, so I think I'm going back to fossil oils this coming oil change. Too many distinct sounds to choose from, makes me crazy!! :-)

[Melas]

Oh cry me a river. Lol. I have a Sportster with forged pistons. I gotcher top end noise. I need loud pipes just to cover up the piston clatter.

[StarfireIV]

I have heard of this happening on Milwaukee bikes more than once. It seems the penetrating capabilities of synthetic oil loosen EVERYTHING up real well. As a result, your bike may be running more smoothly and be far better lubricated, but it will sound like someone shaking a tool box and possibly wind up proving that those new oil gaskets H-D has come up with can still be bypassed.

[brianl703]

Why use that overpriced HD oil (synthetic or regular, it is overpriced) when a 15W-40 dual rated CI-4/SL diesel/gasoline engine oil like Shell Rotella or Chevron Delo is $6/gallon? It has NO friction modifiers to cause problems with wet clutches, which is the only reason I've ever heard to use special "motorcycle" oil. It's also got significantly more detergents and ZDDP anti-wear additives. (The API was concerned about ZDDP's effect on catalytic convertors so typical gasoline engine oils have reduced levels of ZDDP).

Lots of information on this at the http://www.bobistheoilguy.com website -- check the motorcycle lubrication forum.