When I bought my Chinese SKS in 1993 it was well greased internally, I did not service the gas piston for 2 years and it seemed fine, but sooty, when I cleaned it. Greased the gas piston, then serviced it 3 years later, etc. My arsenal rebuilt Russian was bone dry, after greasing the internals, I ended up greasing the small gas piston rod interlink (inside the rear site area)between the main rod and the bolt body, as it was only lightly lubed by the Soviets.
Bought an unissued Yugo recently, heavily greased in the bolt/action area, I removed some of it, have not had the gas piston assembly open yet, when I first fired it the grease was just spilling out of the gas piston cover vent hole so I figured it was ok. But I have been wondering about that middle rod inside the rifle, I suspect that it is greased alright. Anyways, I try not to open the gas piston rod cover assembly as much as possible as it will bell out the mouth, so I only service it every 2-3 years on those types of guns consuming an average of 200-300 rounds a year.
The Yugo has a different shaped/made gas piston cover mouth, it looks heavy duty. Has anyone flared out one of those? Is the whole interior of the Yugo guns well greased when unissued? I have read that some people leave the gas piston dry, and others say lightly oil it. I figure the grease would help preserve and lubricate it. And the SKS's did come greased from China and yugoslavia.
Thanks