On my Iron I switched to synthetic and the HD dude said it will be "noisier". The sewing machine sound you get from the top end was a little more obvious but not by much. Add exhaust and you will not notice.

 

Oil types are about friction, not noise. Motul 20-50 full synth in heavy heat, yes makes noise, due to heat, regular dino would burn-up but the Motul keeps her running, at 140K.KM have had no problems, smoke etc.

I personally suggest after 5000 miles or after break-in switch to 100% synthetic oil to retard friction.

cheers.

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Thanks everyone. Looks like synthetic is the consensus. I appreciate everyone's input.

 

Use what you put in your HD