i think the oiling of carts has been misunderstood
it is really for the internals of the gun and the best way to do that is by using the CO2 as a carrier
so, when, The 850 Forum was around the biggest problem was the 88gr cart seal
so a little oil on that would be fine and in the adapter sure why not
they made a mistake when making the valve, they should have cut the cart opening to hold 2 seals and that would have helped seal the cart neck better
i have a .177 and .22, 850 and the .22 leaked when i got it and Umarex said send it in and we will replace the valve and a new valve at the time was far less then the shipping 2 ways so i ordered a valve
some people will tell you the valves are easy to get out but i will not be one, without help to have someone hold the gun it was a not go for me
now this will be just info
the valve takes a 22mm socket and i have a butterfly air wrench in 3/8 and the valve just came out
now if you have the valve out the opening can be as hard, and you need a pin wrench or make your own and that is what i did but for a socket
i got some 1 inch hex bar stock and a 1 inch socket
i took drill bit ends 3.5mm for the pins and there is a fact that the valve stem should be push in when taking apart the valve so a pocket was drilled in the bar stock
so now to take apart
valve in vise tool pushed on valve end and hit it with the butterfly wrench
now some or all of this is just info but for the tinkerer in could be useful
one other note once the valve is opened, they have a bad habit of leaking and pipe dope has been the way to go on the cap threads
here is the wrench