I added oil to my Cadillac and it drained onto the ground

test the sensor and wiring connections

WHICH DRAIN PLUG. RADIATOR OR EXPANSION TANK

You said it was overheating and oil is milky, sounds like antifreeze in oil, possibly crack in head gasket.

Sounds like you need to drain all the oil out and check for particles in the oil. Some of the new oils have a "cleaner" in them and will loosen debris in an older tranny which will block ports in the tranny. If so... try flushing the tranny with a cleaner availble at most Auto stores. Ask the dealer (preferable a older one who knows about older cars if this will work)!

If your at home changing the oil, how would you
get under it to work on it,change the oil ,etc, without
raising it up & supporting it on quality jack stands?

You would be better to put it on the ground level when
you have added the new oil & are going to start it, verse
leaving it on stands at an angle

Have to add oil to the new filter

well let me see you have 4.6L engine you need 7.5 quarts of oil with new oil filter.to do the oil change you need large drain pan and oil filter wrench and a metric wrench to remove oil drain plug you need a funnel also.you need first start engine let it run for 5 minutes to warm up thin out the oil so it will flow better.once engine warm up.turn off the engine.open you hood.now safely raise support vechicle on jack stands make sure vechicle parked on solid level ground.place large drain pan under oil pan remove oil drain plug you need a 15m wrench remove drain plug let all old oil drain out until you see slow drip then reinstall oil drain plug dont over tighten drain bolt.then place drain pan under the oil filter then remove oil filter using oil filter wrench or large channel lock pliers.once you remove oil filter wipe oil filter seal surface with clean paper towel.take new oil filter add oil to new filter then install new oil filter hand tight take filter wrench turn oil filter one half more turn dont over tighten will damage oil filter seal.make sure oil pan drain plug is in place. then lower vechicle. remove oil filler cap on the valve cover add new oil to the engine using a funnel to keep from spilling oil all over the valve cover and exhaust manifold.add all 7.5 quarts to oil crank case wait until oil settle down in crank case check oil dip stick oil level should be at the full mark on oil dip stick.dont over fill crank case.once you finished oil level correct crank engine check for oil leaks at oil filter and oil drain plug. if engine running okay you see no oil warning lights you ready wheel and deal.

If this is one of the front wheel drive v-8 models, there is a problem with the rear engine seals on some years. The seals open when the engine is hot and allow oil to drip. As the engine cools, the seals rejoin so the leak hides. Sometimes, all it takes is to retorque the existing sealing surfaces.
It may also be valve cover gaskets. The fan and motion of the car will cause these to run the dripping oil along to the rear of the motor like a rain gutter, then onto the exhaust and ground.

When you change oil or flush YOU dont take off the pan to clean it out as Flushing is the worst thing you do to a engine unless you are thinking of rebuilding it .
All you do is to drain ...by using the drain plug and let it drain for 10 minutes ,,while draining change the filter AIR and OIL put bung back in and refill with 20W40 or summer 20W 50 oil .
SO NOW YOU HAVE A OIL MIXED WITH FLUSHING GUNK ???????????????????

reduce oil would indicate that probably too much oil was added into the engine. park vehicle on level ground and check the engine oil level. it shouldn't be past the full mark on the dipstick..if there is too much in there, you will have to drain some...two way, siphon out of oil dipstick tube (hard but not impossible) or open the oil drain plug at the bottom and drain some of the oil..

good luck.. if still have problems, post it up
cheers bry

The oil drain plug is located at the bottom of the engine under the car It should be a bolt directly in the oil pan that would be your oil drain plug.