When I get a chance this week, I’m going to pull off the oil filter and check it out. I’m kind of thinking the timing of this might have been around when HD went to the longer oil filter.

 

switched to the new one when they came available and have used them several times..no difference..same several seconds of noise then quiets right down as designed and HD states

 

I run synthetic Mobile 1 in everything. It's noticeable thinner than non synthetic. The engine that I rebuilt in the Jeep (had high mileage and lost a freeze plug behind manifold and ran hot) rattled on startup after about 20K.
(Mobil 1 10W30)

Piston clearance was at max when I put it together. Mains and throws were mid tolerance. (I used two size shells to get it right on throws.)

I changed the oil to 10W-40 diesel oil. Cut it out.

Obviously, you can't see it on a Harley but on a car motor it's clearly visible to see the piston rock from one side to the other at the bottom of the stroke. You can easily see and hear .003 before the piston gets some heat into it.
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It's a rattle. Aluminum on steel. Lifters if down slightly or a aftermarket cam that does not have a lead for bleed off during lift sounds like a ballpeen hammer on a steel table. Steel on steel.

If it sounds OK after a few minutes of running, it not going to blow up.

 

Check the exhaust crossover, the bracket/hanger is loose fitting for expansion and it sometimes makes a rattling sound.

 

Lifters, my woods Alpha directional where bad from day one when we did my 128 kit. Replaced under warranty and 0 noise on start up now

 

my rattle turned out to be the fuel cap chattering 😊

 

Do you know how much of a mess your gonna make? Just grab one at the dealership and take a look…

 

The revised M8 filter has increased capacity and a change to the bypass valve, Anti-Drain back functions the same as the previous version.

The changes made to the M8 filter lead me to believe the old version was spending too much time in by-pass

 

Harley filter, does not rattle, never did.

 

You do realize weather it goes thru filter media or thru by-pass, it all goes in the same direction. Keep in mind, restriction increases pressure by reducing volume.

Harley's with piston cooling injectors are designed around having a certain size dual rotor pump, relief in cam plate and in the oil injectors. They work best also with proper oil viscosity. (20W-50)

Oil injectors do not work at idle oil pressure.