Oil type 1/2 h.p. ace sump pump type of oil in the main body of the pump.

It is called Di-electric oil and it needs to be completely filled up and possibly a new gasket if it doesnt seal correctly.

Most sump pumps are sealed so they have no way to add oil. I would see if your pump discharge line has a check valve installed in it.It should have a check valve installed so that waste can only flow away from pump.Otherwise the pump can cycle for a short period,shut off and have water in vertical pipe flow back into sump basin causing pump to cycle again. Also if your pump does have a check valve in it make sure that it doesn't have anything caught in it that would stop it from closing completely. Some pumps have a check valve installed on the pump. It is also possible that you may have something caught in the pump impeller. you will need to remove pump to inspect the impeller. Hope this helps you. Thanks

That's the idea; if you lift the float the water starts pumping because it works off of that float. That type of pump is usually meant for water that is in a tub or bucket, so that when the water reaches a certain height and causes the float to rise allowing the pump to kick on. I use a pump like that to pump our the drained water from my washing machine in my basement, i let the water go into a big 50 gallon drum and then once the drum is half full i have it set so the float rises and pumps out the water. That being said, if you are putting this in your basement at floor level, you would need to get a 10 gallon bucket meant for sump pumps (you can get one at your local home store) and rent a jackhammer if your basement is concrete and put the bucket in the floor and the sump pump in the bucket, this is called a sump pit. Another option is to get whats often called a "floor ******" pump. Its a pump that sucks the water out when it reaches around a half inch of depth and it can be used in several feet of water (I've used these as well, there is no float involved), and it can be set on level ground there is no sump pit needed. The one thing with my pump you may not want, is that it's constantly running because its constantly monitoring for water so that a lot of water will not build up (especially if water can damage some thing in the surrounding area) . You can check out all the types at your local home store.

possibly the mechanical mechanisim that is attached to the water level indicator is not switching your pump on properly. could be broken internally or the linkage is set up wrong.
of course there may be other issues like the power source or the motor itself or the thing has siezed up.

Do you mean it won't pump last inch of water or so? sump pumps are not designed to pump completely dry. vane pumps will pump dry. If you are pumping from one tank to another and after pumping is complete, and fluids transfer back, install a check valve on output hose to prevent back-siphoning , or don't submerge output hose on other tank. Hope this helps.

The switch has failed. Replace it with a new mercury type rated to handle the pump.

I have a master plumber 1/3 HP model 539892 submersible effluent pump and was wondering if it takes oil and if it does what type of oil.

No because the water temp will keep it cool and there is a safety factor built into the pump

I have been in this business for a ong time 34 years by the time ou take the pump apart and find the right peices it would be cheaper to buy a new pump, suggest zoeller submersable pump,,

The higher you pump the water, the stronger your pump needs to be, or the skinnier your hose needs to be. A lower discharge point and / or a smaller diameter hose might help immensely.