This is the jack I bought from Craigslist. I believe it is a harbor freight jack. I can not open the links provided from this computer. Will this jack work?

 

My sears jack works great with the frame protectors, but lately I notice it is starting to not hold its height( I do use the safety) . I checked the oil and it seems ok. There is another screw that says do not adjust. Could I tighten it and have the jack stay up. Or should I change the oil. Or any other adjustment.?

 

The oil should not require change unless you have a leak.