Hydraulic cylinder treatment?

[Bruce Parker (RIP)]

Where you have a hydraulic slave cylinder with fluid on one side of the piston and air on the other, is there any coating or treatment for the exposed cylinder on the air side? Movement of the piston will keep the fluid side clean but air and residual fluid tends to rust the cylinder that doesn't see any piston travel, rubber bellows or not.

Is there a coating (lithium grease?) or something else you can use to protect this surface?

Where I'm experiencing a problem is the clutch slave. The inner portion is fine but rust & crap builds up just beyond that where there is no travel. As the clutch wears changing the throw, the piston now has to ride past the sludge/rust causing fluid leaks and ultimately failure. As fun as it is to remove and clean hydraulic cylinders, doing so as few times as possible would be nice.