I take it you took pics of the bottom of the cylinder because that is where you determined the oil to be leaking from? I don't think any additives are going to be of any help, from the sounds of it, it is leaking pretty fast. You may be able to buy some time by re-torquing the bolts at the base of the cylinder, and popping the valve cover off and re-torquing the nuts on the cylinder studs. You will need the torque specs and sequence for those nuts and bolts and you will likely need a new valve cover gasket. I don't think I would waste my time with that option though because it might not work, it will likely cost you around $20 if you need to replace the gasket and you will probably have to buy it again when you go to fix it properly. If the gasket is just blown out, this will not help and replacement is really your only option. To replace it is as simple as pulling the top end off and replacing the gasket. Since this is not an OHC engine, there is no timing chain to mess with, so it is relatively simple compared to other machines. The old gasket is most likely going to be ruined when you remove the cylinder, so cleaning it off will not be an option, I wouldn't try to re use it even if it did come off in one piece. You will need to replace the head gasket as well and likely the valve cover gasket too. Once again, you will need to have all of the torque specs and sequences to properly re-assemble. If you don't have a repair manual, I would order one. Ebay has decent prices on repair manuals and you can probably find a top end gasket set there too. If it were me, I would just tear the cylinder off and replace that gasket first thing. Good luck.
Yours truly, sincerelly, love always, Josh aka The DirtDemon.