Originally Posted by AttackHelicopter
I’ve noticed when I fire my car up, it spew a good cloud of white smoke out from the exhaust. Anyone know what this is? It’s not an excessive amount. But more than I feel like should come out. Idk I’m car retarded. 19 RT M6
Some areas of the country have climate that is quite conducive to an engine producing water vapor (white "smoke") upon cold engine start and for a bit after.
This is normal and nothing to worry about.
One way to possibly distinguish between water vapor and oil smoke is water vapor dissipates quite quickly while smoke doesn't even if there is a bit of a breeze.
In some cases a bit of oil smoke upon cold engine start is normal, too. In some cases the mechanism for removing oil vapor from the crankcase fumes is not very effective and some oil vapor makes its way to the engine intake. Because of the way things are designed the fumes from the crankcase have to make one last sharp turn when they leave the hose from the engine and enter the intake system. The oil vapor being heavier doesn't change direction as readily and some oil vapor impacts the intake wall opposite where the crankcase vent hose connects.
If the engine continues to run this vapor now liquid oil again will get pulled into the engine where it is burned. Because the engine is warm as are the converters there is no smoke. And the amount of oil burned is really quite small.
But if you park the car the heat soaks the intake and this warms up the oil on the intake walls. This oil will run down and into a cylinder if the intake valve is open or puddle on top of the intake valve if it is closed.
Upon cold engine start this oil is not completely burned and a bit of smoke is the result. This looks disturbing but really isn't anything to worry about provided the smoking is over with as soon as it starts and the engine manifests no signs of any trouble and the CEL remains dark. Techs see this smoking behavior all the time due to the usage/treatment new car engines get on the lot. (Infrequent running and almost always for rather brief periods.)
Couple of things you can do to reduce the likelihood the engine will smoke at cold start. Try to avoid short trips. The longer the engine operates and at its normal operating temperature the less likely there will be any significant amount of oil on the intake to run down into the engine when it it shut off.
Avoid running the engine hard then shutting it off right after. For one thing you really should give the engine some run time to shed the considerable heat load it develops from hard running. The other thing is generally hard running produces more oil vapor and this means more oil on the intake walls. By giving the engine some run time after hard running this gives the oil on the intake walls time to make it through the engine, the hot engine, so the oil will not be there upon cold start.
Do not overfill the engine with oil. I like to run the oil level right at the full mark -- check the oil level with the car level and the engine up to temperature -- to ensure plenty of oil for the engine's needs but overfilling can result in more oil vapor.
Run the correct oil for the engine.
Do not run the oil too long. As oil accumulates miles it accumulates contamination from combustion blow by. Some blow by is normal and the contamination is normal. (It is dealt with by regularly draining the contaminated oil and replacing it with fresh oil.)
But between oil changes the contamination results in more oil vapor production. No need to go overboard with the oil changes but adhering to the factory oil change schedule -- at least -- goes a long way to keeping oil vapor production down.
As an aside, with my other cars I could tell the oil was due to be changed even without looking at the odometer. The sign was upon cold start the engine would smoke a bit even though I followed a more aggressive oil change schedule than called for by the factory and avoided the other things that could lead to smoking. But even so as the odometer got closer to the 5K mile mark at which point it was my habit to change the oil the cold engine would smoke upon startup.
Might mention a new engine is pretty hard (so to speak) on oil and my advice is unless forbidden by the owners manual to have the oil changed early. In the case of my Hellcat I had the oil changed at around 500 miles, again at 2K miles, then at 5K miles and since then every 5K miles.
Currently the Hellcat odometer is around 13,000 and I won't get it to 15K miles and the next 5K mile oil change interval before 6 months since the last oil change so to adhere to Dodge's oil change interval guidelines I'll have the oil changed at 6 months -- later this month probably -- and with not much over just 3K miles on the oil.