Keep the chamber clean, this mechanism works by gas lubrication, the upper 2/3 rds of the case is floated off the chamber walls.
If you allow the flutes to become clogged by firing ammunition which has tar sealant around the bullets, cartridges will stick in the chamber. So basically, keep the chamber clean and the flutes clear.
I do recommend using grease on the bolt rollers. I had to buy the special extractor spring compression tool to re assemble my bolt head, the spring is so strong, but grease the bolt rollers. This is a mechanism that prefers light greases to light oils.
I think the roller bolt mechanisms are an amazing intellectual achievement. The Germans got the part count down, designed a rifle that was quick to manufacture, simple to operate, simple to maintain, reliable in function. Of the 7.62 Nato battle rifles from the 1950's, it is still the only one still being issued as a standard service arm.
I do recommend the port buffer