Until today, I thought oil expander rings were ALL non-directional.

I noticed a ring manufacturer indicate that on their piston ring set instructions that the oil expander (the bottom wavy ring) is indeed directional. This really surprised me.

The issue is where the ENDS come TOGETHER.

In searching online, I've found two diagrams showing the opposite recommendation of each other.






I know, I know, just follow the directions...

But what is the thought behind this? If you install a compression ring upside down it will push oil towards the combustion chamber, a big goof, but what about the expander ring installed upside down?

Any thoughts or explanations?