From the Kohler CV-15 Service Manual - Page 6-1 - Check Oil Level: . . . . . 3. Unthread and remove the oil fill cap/dipstick; wipe oil off. Reinsert the dipstick into the tube and rest the oil fill cap on the tube. Do not thread the cap onto the tube. See Figure 6-3.
When checking the oil, "Do not thread the cap (dipstick) onto (into) the tube." If you did thread the dipstick down to read the oil level and the oil level was correct, then it would cause the oil level to appear to be over full. If you did screw the dipstick down every time to check the oil then you'd actually be under-filling the oil in the crankcase and it would never really be up to the true full mark.
I have always had Briggs & Stratton lawn mower engines and I have always screwed the dipstick down when checking the oil level and I have never read this same oil check instruction in the Briggs service manual and I am 70 years old.
My current engine, on my 1992 33" Snapper Series 14 RER, is a good 1993 12.5 hp "L" head Briggs but I also have this spare NOS 1997 CV-15S Kohler with 3 hours on it. My brother gave it to me about 10 years ago, still in the box and it still hasn't ever been installed onto anything, but hopefully it will end up on my Snapper this coming winter.. So, I'm very glad that I found this tidbit on how the procedure for checking the oil on a Kohler is different from the Briggs & Stratton procedure.
By-the-way! I've found out that the wiring harness for my Snapper, with the Kohler engine, is different from the wiring harness with the Briggs. I would appreciate it very much if you know what the wiring differences are between the 2 engines that you would please share it with me.