you can take oil and put it where you suspect there to be a vacuum leak. If there is a leak the oil will be pulled into the engine or hose
the way you can see if your car has a oil leak look on the ground to see if there is a spot before you put
Check the oil cap and the drain plug, as well as the oil filter.
You cannot check the fluid level as the transmission is a sealed unit. A GM dealer can check it if you have a leak. If you have no leak then it is fine.
Obviously your oil has been leaking out. Check the oil level and fill to specs. Also you need to fix the oil leak.
Check the oil pump housing gasket
Shampoo the engine to clean it. Check for leaks in a day or so depending on how bad the leak is. Replace the component causing the leak. If you still can't find the leak you can put dye in the engine oil and look for the leak with a black light.
You have a leak and a large one. If you or a cheap store just changed oil, then they may not have attached the Oil Filter or the Oil Pan Plug correctly. If you leave off an O-ring or don't lube the gasket on the oil filter, then it could leak. Generally this will not leak very fast. The oil pan plug is at the bottom of the oil system and it would leak out all of the oil. Check your radiator water. Sometimes an engline will leak oil into the coolant system and it will be carried to your radiator. This will turn the water a chocolate milk color.
Type your answer here... Check for the most obvious. Oil filter not on tight, oil drain plug not on tight, leak around oil pan gasket. Also, if you have over 100,000 miles on your car, valve cover gaskets are known to leak.
The oil could be getting into you coolant system. Check to see if your radiator fluid is milky brown.It could be a leak that only happens when your jeep is in motion.
Check for a gasket or O-ring on the cap ( it should have one ), also check crankcase ventilation.
You can't it is a sealed for life unit. Your GM dealer can check it if you have a leak.