Milky engine oil can sometimes be normal and sometimes milky engine oil can be an indication of a serious problem with your engine.
When engine oil gets milky it can be as simple as moisture in the oil through the natural combustion process of the engine.
Sometimes when you're driving short distances you don't get the engine up to a hot enough temperature to evaporate that condensation which then gets into the oil and causes the oil to look milky.
When you get out on the highway and drive the vehicle then the engine oil should turn back to normal.
If that is not the cause then you may have a blown head gasket that is leaking your coolant into the engine cylinders which then gets sent through the exhaust and then some of the coolant winds up in the engines oil as well.
If you start your vehicle and notice white smoke coming out of your exhaust then you likely have a blown head gasket.
If it's a blown head gasket that is not too bad yet then you can use Bar's Stop Leak Head Gasket Sealer which I've used with great results on small head gasket leaks.
You mix the head gasket sealer with 3 quarts of warm water and then shake it up really good.
Then drain all the coolant from your radiator and flush the coolant out of the engine.
Next pour the head gasket sealer mixture into the radiator and add more water to the radiator and then start the engine and let it run for 5 or 10 minutes at idle.
Then shut the engine off again and let it cool down and check the water level again and if it needs more water then top it off and start the engine again and go for a drive of around 10 to 20 miles to allow the head gasket sealer to work it's way through the engine.
If the head gasket leak is minor and you follow the directions on the bottle then it will work but if it's a bad head gasket leak then you need to replace the head gasket.
Another cause on some engines for milky oil is an intake gasket leak which then fills the oil pan with water and if it was an intake gasket leak the oil would likely look a brown like color and your oil pan would be filled with water.
Drain some oil and see if any water comes out and if so you have either an intake gasket leak or a head gasket leak which needs fixed before the contaminated oil damages your engines bearings.
If it's just condensation then there's nothing to worry about.