CO2 is on the other side a perfect fire extinguishing gas.
I never encountered a dieseling effect, and I dare to say that some of the rams I did build are strong and fast enough to get that effect.Actualy not. In a CO2 system there is no free oxygen to react, and on the non pressured side of the piston we dont want to have any pressure build up.
I would be surprised if we get a diesel effect in a good designed and build Full pressure CO2 using system. Is that a Gravity or a Dantomkia setup.

I use the very sticky molycote 111 silicone grease in my rams. And the Burkert valves are equipped with sealing materials that can stand a lot off chemicals. But Silicon grease/oil is mostly the safest bet you can make.