1970 383 Oil Dipstick Reading Anomaly

[jimkf]

So if I let the car - a Coronet wagon with a two barrel engine - sit for a couple days and pull the dipstick, one side shows the oil as black while it shows as clean on the other. The oil was recently changed and has less than 300 miles on it.

One thing to note, the engine runs but had developed a rod knock. The dipstick display oddity was happening prior to the knock developing which is what prompted the oil change. The oil that came out was clean. There is no mixing of oil and water happening. The coolant is clean and the level in the radiator has not changed. I’m stumped.

Thoughts?

 

[1STMP]

I have the same thing happening in
my 440, though it's newly rebuilt. My
first guess was dried lithium grease
particles suspended in the oil and
slowly settling on top of the dipstick
after the engine sat for a while.
But after seeing the same thing
happening with your engine, there's
a couple more things to consider.
This is a wild guess, but it could be
the dipstick is mildly magnetized
and very fine metal shavings are
being attracted to it, or if you're
adding ZDDP, the heavier
compounds of the additive are
settling out of.the oil.
It hasn't affected the lifter function
in my engine, and it doesn't show
up in my oil filter, so I'm not too
concerned about it.