In this case turn the jack upside down and drain the contaminated oil fill the jack with the new oil up to the required level.
Floor jack fluid fill.
The hydraulic fluid is compressed inside the floor jack and this forces the pistons to rise and this pushes the saddle to lift your vehicle.
How to fill a floor jack if you own and use a hydraulic floor jack you will want to ensure you keep the the hydraulic fluid level at full for proper and safe operation.
Once you buy a new floor jack you may use it for 2 to 3 years without having to refill the hydraulic oil.
Oil contamination could also be one of the reasons.
Then remove the plug or screw from the oil.
Once the jack is lowered locate the oil filler port which is on the bottom of the jack s reservoir near the flat base.
To add oil to a hydraulic floor jack start by making sure the jack is completely lowered by turning the jack s release valve counterclockwise until it s as low as it can get.
As a matter of fact without the hydraulic fluid the hydraulic floor jacks cannot work.