Di Odd colored fluid on the top of the piston

[Boyd12]

I have a 951 Di and below is a poor image of what appears to be greenish fluid on the top of the pistons (both equally). I have NO idea what it could be. Any ideas?
THANKS!

 

[mikidymac]

Moisture on oil which is common on the 951 and why it should be fogged after every use.

 

[Boyd12]

The fluid looks to be green/brown; I don't know how this could occur, but could it be balance shaft oil getting into the combustion chamber? The engine passed the leak-down test.
Does adding moisture to red SD synthetic oil cause it to change colors?
Could it be fuel related?
My concern is that I do not smoke an engine due to something fixable!

 

[mikidymac]

It’s oil and fuel and water. All the 951’s do it because somehow they get moisture probably from the exhaust.

This why you have to fog.