Do not use regular oil, only use Crosman Pellgun oil or RWS pellgun oil. It can be purchased at most sportingoods shops that sell pellet guns. You can also order it online (See the link below.)
Crosman does not own Marksman. Crosman made a Repeatairmodel and Marksman made a Repeater model. See the link below for the Marksman Repeater owners manual.
There is No C02 cartridge in the Marksman Repeater, it is spring operated
The Marksman repeater is rated at 200 FPS.
The Marksman 2002 Repeater is rated at 250 FPS.
There have been several models of the marksman repeater. The first one was made in 1955
18 BB according to Marksman
Do not use 3in1 or gun oil only use Crosman pellgun or RWS oil. lubricate all the moving parts with a little oil not too much.
See the Link below for the "you tube" video for Marksman
See the link below
It is rated at 200 FPS
Needs to be serviced/repaired