Sorry, I don't know the answer to your question, but, in similar situations, I've had pretty good luck finding owner's manuals on line.
Jim

Two options: take apart if you are handy and clean all the gunk out of the cylinder and off the gasket. Then oil it all while you have it apart.
option #2: Any petroleum product will work. 3-1 is a little thin but it works fine but you need to add more frequently. It only requires a few drops each time. Then pump the several times to make sure you coat then inside walls and the gasket well. If you don't use it often you may need to add a few drops with each use. If used monthly or more then a few times a season should work fine. Gasket kits can be bought for most brands but if you use the oil regularly you should get many years without replacement. The first key is to be careful to keep dirt or gritty matter out as you add spray material. Always clean and triple rinse your sprayer and on the second and third rinse pump it up and spray the clean water out of the wand to clear gunk out of spray head at the same time. Good Luck and Happy Growing David