Auto Parts: HYDRAULIC FLOOR JACK, grease fittings, grease gun

Question
I have a HYDRAULIC FLOOR JACK, by Sears, capacity 4000lb, #241-50113, 5 1/2"-14" range; code date: 6-89. I left it under the deck outside for a while and it seems rusted. It does not raise if I push up/down the bar. I applied liquid wrench to try to loosen but it still does not work. Any idea to get it work again? Also, where is the release valve to open and fill the oil? Is it the same screw to loosen to lower the jack?

Answer
    Well, I can't say I know about that specific jack.  But, if we're talking about a regular trolley-type floor jack with two big wheels up by the lifting pad and two swiveling wheels back by the handle then, well, they're all pretty much the same.  There should be a small cylinder under the handle that pumps fluid into the larger cylinder, making the working piston extend.  The reservoir surrounds the working piston, and should have a small screw or a little rubber plug through which it can be filled (on most jacks there is a hole in the platform allowing access to the filling hole).  You need to hold the jack so that the filling plug is the highest point before you open it up and pour in the new oil.  You must use "hydraulic jack oil," which all auto parts stores carry.  The rubber plug is usually painted over when the jack is made, so you'll have to look close, but it should be fairly easy to locate.  While you're at it, hit all of the moving parts with a little motor oil to lubricate them, and, if you see any grease fittings (some have them, some don't) hit them with a shot of chassis grease (or whatever grease you have in your grease gun).