Also place the jack somewhere that can get dirty, just in case you spill some oil. If you don’t want oil in your driveway, try doing this in the street.
If you’re unsure how your jack releases, consult your owner’s manual. Keep the release valve open while you work.
Depending on the type of jack you have, the cover plate might come off entirely or just lift up. If the plate comes off, keep it in a safe place so you don’t lose it. Usually these screws require a Phillips head screwdriver, but check your particular model to see what type of screwdriver you need. Don’t lose the screws you remove. Keep them in a safe place so you can put the cover back on later.
If your jack is old and there is a lot of caked on dirt around the fill plug, try spraying a hose or pressure washer to remove the gunk first.
If you can’t locate the filler port, check the owner’s manual for your jack. Be careful not to damage the plug when you remove it. If it doesn’t come out easily, stop and reassess what you’re doing. Don’t force it out.
Use a funnel to avoid spills. Do not use any other type of oil besides hydraulic jack oil. Motor oil or brake fluid will not work.
Do not replace the cover plate yet. You still need to bleed the air from the mechanism before moving on, and the cover plate will get in the way. Depending on the jack model, you may also have to keep the fill plug out while you bleed the air. Consult your owner’s manual for the correct process.
The bleeding process is important because air can build up in the hydraulic system while you change the oil. If air is in the system, the jack won’t rise properly and could even collapse. Bleeding the jack removes the air and makes the jack function correctly.
Some jack models have different variations on how to bleed the air. Check with your owner’s manual to see if your model uses a different method.
If the jack is jerky or doesn’t rise to the top, there is probably still air in the system. Repeat the bleeding procedure in this case.
