here is hoping it is a head gasket.
it could also be a cracked block,or a cracked head.
The steam engine made possible for the invention of the steam locomotive and the steam ship. The gas and diesel engines made possible cars, trucks, diesel-electric locomotive engines, diesel-electric submarines, airplanes made flight possible, and the list could go on and on....
The main difference between a diesel and a steam engine is the diesel engine is an internal combustion and the steam engine is external combustion.
Steam (White Smoke) coming from the tailpipe is the #1 indicator.
Most gasolines have a high water content,When they are burned in the engine the water turns to steam and goes out the exhaust.As the exhaust system cools off, the steam condenses and water can run out of the tailpipe
Steam from the tailpipe, and water in the oil means you have a faulty head gasket. Not a good thing. The steam is the antifreeze/water coolant leaking into the heads (bad gasket) getting heated by the engine and coming out as steam. The water in the oil is the same deal, but it;s collecting in the oil so it isn't coming out of the tailpipe. You need a new head gasket. I promise.
It depends from where it emitting it. White smoke could be steam if from the front - check radiator White smoke from underneath could be transmission fluid White somke from tailpipe could mean burning oil.
It is NOT steam it is vapor, the same as looking over a lake when the ambient temperature is cooler then the lake water
White smoke is steam. A little is normal on all engines. If there is a lot it could be an indication of coolant getting into the exhaust, possibly from a failed headgasket.
The Diesel engine
Of an individual diesel engine and an individual steam engine of the same energy output the diesel engine would be less polluting. It is far more efficient. However, there are far more diesel engines than steam engines in the world today so overall diesel engines pollute more than steam engines.
Steam, diesel, electric, sail, gas turbine, maglev and railplane (1934). The different kinds or steam locomotives, diesel locomotiveas, etc. There are three diffrent types: steam, which isn't used much nowdays, diesel, which burn diesel to run power generators, and electric, which run on electricity.
Could be that your head gasket is beginning to go. Does it smell strongest when you first start the car, then go away? Look for excess steam coming out the tailpipe when you first start it.