Cosmoline or Ethylene Glycol



The exterior of my 2006 Subaru Outback(17K miles) smells like maple syrup after the engine has warmed or even after it’s shut off for a few minutes.

After looking online I discovered that it could be ethylene glycol leaking from somewhere. When I spoke with the dealership they told me that it is simply the cosmoline that is sprayed on the bottom of new cars. Could one really be mistaken for the other? Ethylene glycol is toxic and if it is leaking I can’t imagine that it is good for the environment or my family.

Any suggestions as to how I can tell the difference would be greatly appreciated.


If I’m not mistaken, ethylene glycol is “antifreeze,” and if it’s leaking you should be able to see spots under the car and the coolant level in the radiator should be going down. This would be a warranty issue. Have you checked the coolant level?

I’m not aware of any automaker coating the bottom of their cars with cosmoline. The vehicle was rustproofed at the factory (NOT with cosmoline), and nothing else is needed. You should not be able to smell the factory rustproofing when the engine warms up.

If the dealer installed additional after-market rustproofing perhaps that’s what you smell, but after-market rustproofing is worthless and often makes a vehicle MORE prone to rust.


I’m not sure what cosmoline smells like, but I KNOW that ethylene glycol (antifreeze) has a maple syrup odor. Don’t let the dealer bully you on this issue.


Cosmoline, now there is a hot one. I think not.

Your description of the smell does sound like coolant. I suspect that is exactly what it is. You need to check the level right now and if it is low or if it starts getting lower, you found your answer. If fact when you take a look at the overflow tank and when the car is dead cool, open it up and take a whiff. I suspect you will answer your question about what the smell might be.

I am guessing you are still under warranty, so be sure to get everything in writing from the dealer and keep all the records.


Ethylene Glycol is a kind of sugar. It smells just as you describe it. Get yourself a nice, big, clean piece of cardboard, take the car out and get it nice and hot and then park the front of the car (from the front to about where the dashboard is) and leave it overnight. You will probably find a nice green or pinkish stain on the cardboard.

ps cats and dogs are attracted to puddles of antifreze because it tastes sweet and it will kill them. g


Ethylene Glycol is engine coolant (anti-freeze) and has a somewhat distinct sweet smell to it.

The Cosmoline part of this should be taken with a grain of salt, a large one. As far as I know, no car maker has used Cosmoline on a civilian vehicle.

Cosmoline is a preservative to prevent rust and was commonly used in WWII to pickle spare parts for the military. I’m an antique Harley guy and I’ve got some Cosmoline coated NOS (New Original Stock) parts and Cosmoline has no smell. It would if it were burning off an engine or exhaust, but I do not remember any civilian car maker coating either their parts or their cars with Cosmoline.

If this is a coolant smell that you’re getting then you need to continue to pursue this and document every complaint about this. A paper trail is a must if problems develop.
You might also consider calling Subaru’s regional office and get them involved in this. Be polite in your dealings with them and maybe they can be of assistance.


As stated by others, keep an eye on your coolant level, if there is a radiator cap, remove and check the radiator as well as the overflow. With some leaks, you can get an air bubble in the system that keeps growing, so the overflow tank doesn’t go down. Watch the temp gauge as well.

Cosmoline comes in several grades, one grade was commonly used on Japanese cars in the 80’s through early 90’s, but it was only used on the top painted surfaces to keep salt water and acid rain from damaging the paint. Now they use a peel off plastic.


What Japanese cars was it used on? I worked on Hondas, Nissans, and Subarus back then and never saw Cosmoline in use even when doing PDI (Pre-Delivery Inspections) on those cars.
Honda did use plastic covers on disc brake rotors that had to be removed before the car was sold.

  1. It’s antifreeze leaking, and it should be fixed under warranty.
  2. FInd another dealer. That one’s a crook.


Ethylene Glycol is a kind of sugar.

Only in China (they put it in toothpaste, because they think it’s the same stuff as glycerin). EG is not a sugar, but does smell and taste sweet, and kills pets and wildlife that lick up puddles of it. I don’t know if cats will drink it, as cats are said not to be able to taste sugars and sweet things. I almost drank some antifreeze as a kid, from a “fruit punch” bottle that was right next to the picnic lunch…

  1. yup

  2. yup, yup, yup


Unfortunately, the best place to get warranty service done is where you bought the car. Other dealers will put you at the end of the line. Paying customer are first, warranty customers who bought their car at that dealer are second, and other warranty work is last.