I have a Lincoln 2 ton floor jack that I have for the last 5 years that never had the jack oil replaced. I don't have the manual so I'm not quite sure how to go about it.

There is a white plastic nut (11 mm) on top the main cylinder that you are suppose to open 1 turn so air is expelled out of it during use. Occassionally a bit of oil will also buble out of this port squirt well. I suspect is this is the oil filler port but I want to be sure it is not the check or the overload valve. Any help is appreciated.

 

I have never 'changed' the oil in my floor jacks..............I have added "jack oil" in the past. I have never heard of changing it. Perhaps we will hear differently but I do have my manuals (albeit I am far from looking at them) and cannot recall ever seeing a 'chapter' on changing the oil.
R.

 

what kind of jack is it? i mean, style maybe?

such as, a bottle jack
http://www.autozone.com/servlet/UiBr...ELAR%7C%7Etrue
or
http://www.uneedtools.com/bottle-jack-p-423.html

or a racing-style
http://www.autozone.com/servlet/UiBr...ELAR%7C%7Etrue
or
http://www.uneedtools.com/floor-jack-p-365.html

or a floor jack
http://www.autozone.com/servlet/UiBr...ELAR%7C%7Etrue
or
http://www.uneedtools.com/floor-jack-p-876.html
?

i think i know what you mean, if its a bottle style jack. ive never 'changed' the oil, but i have had to refill one before (because i accidently dumped the fluid everywhere).

if it is a bottle jack -

the pressue valve on the bottom of the jack, opposite the jack lever, comes out. WARNING: there is a ball-bering inside of that, so remove the valve with the jack on its 'back', so the valve is facing skyward. take out the screww, then slowly turn over the jack to remove fluid and ball bearing. i would assume the piston would have to be in the full down, or compressed, position, otherwise, when you replace the valve, and compress it, there would bee too much pressure, and bust an o-ring or something of the sort. get jack fluid, and a funnel if your not suave, and pour into that opening which you removed the screw from. fill untill you can see the level, then replace bearing, and then valve.

if its not a bottle jack - i have no idea

 

Reg and Flamejet, thank you for your response.

What I have is a professional 2 ton floor jack---its a big mama. Paid quite a bit of money for it so changing the oil would be a good preventative maintenance. Since it not a sealed container, moisture would have altered the oil composition, not to mention wear and tear. I'm going to take that white nut this weekend and hope it is not the check valve or relief valve. I don't want to deal with ball bearing or springs shooting out.

 

Nothing is going to jump out of your floor jack..........don't worry. The plastic plug is either the vent or your fill plug. Be cautioned that if you get air in the pump by removing too much oil, you are going to have problems "pumping it back up". My advice to you is to simply check the oil and if it is low, then fill it. Now............one last caveat. There are several different hydraulic oils. What I have purchased is called "pump oil" and I do believe that I found it at either Sears or NAPA auto parts. Incidently, Audi used hydraulic oil in their power steering pumps (not the 'American' type such as trans fluid) and if you put the wrong oil in you had major failure!! Audi changed the oil several times over the years. At any rate, your floor jack has no where near the 'wear' factor that one would find in a hydraulic pump that is powered by a motor or engine so I would not be too concerned.
REG