I have many locos with the seuthe smoke units. They work very with lgb fluid but only that.
Last christmas I tried an expermient and put some concentrated pine sent in the lgb fluid. Worked great for awhile then they stated slowing down smoke output.
One got so bad I had to replace it. I would guess the sent had something to do with getting plugged up in the tiny little chiminey they use.
You can get a new one for 9.95 at trainworld. You just need to ask for the 6 volt version. Also walthers stocks them but the 6 volt ones are hard to find until you catch on they are listed under ships etc. They are with all the smoke units but need to look for the smoke unit under ships.
They also want 19.95 for them.
The reason I say this is I love jttrains christmas and vanalla scents but I would advise to not use them in seuthe because of the scent.
In all other smoke units, mth, lionel, TA etc that is the best stuff.
A good working seuthe puts out a good amount of smoke. I use one eyedropper to an empty smoke unite. It comes out to 39 drops to fill the unit 1/2 full. Anymore and it will reduce the output.
Dave.