weird pictures of pistons

Ok here goes. My RV-6A has an 0-360 CS prop 600 hours Channel chrome cylinders burning 1 qt 20x50 Phillips blue bottle in 7 hours. (I figure that's normal for Channel Chrome cylinders)
Compressions cold are 80/78 all cylinders. All valves look real good, No carved up Cylinder walls.
Runs good.
SDS fuel and ignitions systems. Burning Costco premium. Engine operated at 26" or WOT at 2300 RPM.
Question is what are the weird patterns showing up on the tops of the pistons, not on the bottom.
Three oil changes ago I bore scoped it and seen nothing like this
This was just noted a week ago on #1 and 3, Now 2 has the same thing.
I did switch to the Phillips oil, change before last and I change every 25 hours.
Oil testing by Blackstone is good.
I'm posting all four cylinders in firing order 1-3-2-4

Those looks like liquid oil running over the piston crown after shut-down to me.

Are the 'runs' at the top of the cylinders?

Looks like a fuel stain to me.

There is naturally a swirl to the gas flow in the cylinders as the in and out's are at the bottom but I agree that this looks like the oil has dripped/run down the crown.

Have you changed the weight of the oil as well as the brand?

I'm about to borescope mine again but as I've just broken it in expect to see a right mess on the pistons. I'll look out for the pattern though. Interesting.

The chrome cylinders are a different thing though, I used more than you did though on normal cylinders pre refurb so hoping for an improvement shortly.

Regards, Clive

Yes, the stains are at the tops of the cylinders. And as Boyd suggested. I'm now in the fuel stain camp as it correlates with the location of the injectors that are in the primer holes.
I asked an AnP buddy and he goes ""wow never seen those before""
Because of the Channel Chrome cylinders there is slight oil pooling in the bottom of the cylinders any time I look.
My shut down procedure has been to just pull up to my hangar at an idle and turn off the electric pumps and that kills the engine.
But, maybe I need to revert to old school methods and bring the RPM up a bit.
As far as oil brand yes, I changed from Areoshell 20x50 to Phillips 20x50.
But, I've only seen this pattern very lately not after brand change.
I do agree with Steve that it looks like oil washing down from the top of the cylinders. But why? In these weird locations? That's why the question. If it was oil then what the ---- has happened to the rings on now three cylinders.
Gonna put it back together today and wait for good weather then put a few hours on it. Then we'll see if it's fuel stains or not.
I'll post back then
Thanks for the info.
Art