Hey Scotty
My '18 Impreza spews white smoke especially at start up. Currently at 37k. It isn't so bad once its warmed up but still can see it more than on other vehicles. The Dealership said it was just water vapor. My coolant level drops and I have had to add coolant several times but the dealership said that it "evaporates due to the open coolant reservoir." I'm skeptical. It just started using a bit of oil between changes (about half a quart every 5000 miles, 5 quarts full synthetic). I've always been meticulous about maintenance.
Any advice?
Also, the smoke smells like alcohol, burns my nose when I tried to smell it.
In cold temperatures this is normal. Otherwise the head gasket is blown. Can you find any leak under the car after sitting for a long time? Do you see it dripping? Because the dealer is selling BS to you. I suppose it wants to avoid repair. If car is still under warranty, they should fix it for free.
Good luck and don't give up.
Get one of those coolant test kits that Scotty has talked about to check for a blown head gasket:
https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF
No leaks visible. Smells like coolant under the hood after driving, smell comes from near the firewall (heater core?) Smoke happens every startup regardless of how warm it is outside or how warm the engine is. I may need to grab that test kit and dig up the video...
If the head gasket checks out OK you might also want to use a pressure tester on the cooling system. I've found mysterious leaks that were pinholes in hoses an loose hose clamps that way.
Update: to add insult to injury. The engine started using oil. I do my own oil changes and between 4-5 thousand miles it will use about half a qt. The oil drains out foamy and has a slight fuel smell. The viscosity is obviously degraded just by feeling the old vs new oil...
Could I be getting oil dilution?
I will also pick up one of those combustion / dye kits for the HG leak test. Also going to save the old oil filter and oil. I need something tangible to show the stealership when I bring it back so they don't BS me with "We can't duplicate the problem."