Metal in oil

Fittrjoe said
I would call my driving spirited
Once in a while I get on it hard but mostly baby it
I use an oil pan heater when below 60 degrees to warm oil
Mostly trips under 10 miles with a good 2-3 minutes warm up in drive way at idle
I’m 67 and pretty conservative driver
Never heavy throttle over 3500 RPMs
Occasional highway use ( has nice 3:21 rear )
I mean I don’t abuse this thing at all

I run two 340 motors in my toys. One was built in 87' the other in 89'. When I change the oil, I always have that gray slime on the drain plugs. Maybe not as much as yours, but it is there, 35 years. I think the motor is still in the break in phase or you may be getting a little moisture in the oil from not heating the motor up on short drives.