White smoke was coming out of the exhaust

Perform a chemical test to check for a leaking cylinder head gasket. White smoke is caused by burning engine coolant in the engine.

https://www.2carpros.com/articles/head-gasket-blown-test

Please let us know what you find.

White smoke coming from the tailpipe was probably actually steam. A symptom of a blown head gasket, caused by overheating the engine. The oily looking stuff coming out of the pipe was probably water/coolant that had gotten dirtied up by all of the dirt and other gunk that has built up in the exhaust pipe. If you check your oil now, I will bet that it looks more like mud or chocolate milk, because coolant has mixed with the engine oil.

Check the oil and let us know what you see.

Hello,

Please run this test which will confirm the head gasket failure.

https://www.2carpros.com/articles/head-gasket-blown-test

Please let us know what you find.

I'm going to go ahead and say that the gasket is likely blown. If you're lucky, the head itself isn't warped or cracked and you haven't done too much damage to the block running the engine with coolant/water in the oil. Go ahead and confirm the blown gasket, and then start looking for a mechanic to do it.