No. oil and grease are are entirely different unless your axle is a horse pulled waggon and has a wooden axle.
The engine turns off when the oil cap is removed because the engine is designed to do so. When the oil cap is removed a vacuum leak is created which causes the engine to turn off.
When engine oil turns gray or milkey cream color, its a sign of moisture in the oil.
The oil thins when hot and the oil pump is driven off the engine so, the lower the engine rpm's, the slower the pump turns.
engine oil turns black when oil mixes with the carbon from normal combustion inside the engine. this process eventually changes the viscosity of the oil and keeps it from flowing through and lubricating the motor properly.
The engine oil helps in lubricating the machine. Oil helps in cooling the engine and lubricates the moving parts properly. The moving parts are constantly shifting and are connected to each other. Oil is needed to grease the parts so that the components move properly without causing harm to the machines.
When your engine turns over, there is an oil pump inside the engine that is being driven by the crankshaft. It is creating pressure by pumping oil throughout the engine. Most will achieve around 40 to 50 lbs. If there is a problem with any of the lines or gaskets in the system, it will leak when there is pressure. Try to locate the leak by washing the area that's leaking and watch it as someone turns the engine over. Most leaks of this sort aren't too hard to fix.
oil and grease is used in vehicles to reduce friction.
There is a metal caterpillar tag on the top of the engine. It is probably covered in grease and oil so take some cleaner with you.
This could be a problem with the oil pump. Just because you have oil visible on the dipstick does not mean the oil is properly getting to the engine. Have the vehicle serviced as soon as possible to avoid engine damage.
There is no way for grease to be in your oil for your expedition. There are no "grease-able" part on your engine or transmission for that matter. You are probably seeing either gummed oil or perhaps you are having a head gasket problem that is allowing water into your oil. This would make a mixture looking slightly like mayonase in your oil pan and engine. With as many miles as you are describing in your car, it is most likely the case that there is just some build up of sludge from inferior oil breaking down and 'sludging up'
For lubrication. To reduce friction and heat buildup which would quickly damage the engine otherwise.