The smoke is made by burning oil in the smoke generator. Since the "smoke fluid" is oil and not a highly volitile (spelling?) liquid like gasoline or alcohol, it won't evaporate. If you put some in, the only way it would disappear is if the generator develops a leak. The problem with smoke in ho however is that the oil doesn't all burn. Part of the smoke is unburned oil which will fall on your rails and become a dirt magnet! If you use the smoke liquid, expect to clean your track continually. I am not connected in any way with this company, but these are probably the best commercially available track cleaning cars on the market.
Aztec Mfg - Model Railroad Track Cleaning Cars and Accessories
Scotch bright pads will clean your track, but if you are running smoke units in your locomotives, you will need to run some sort of track cleaning car in your train.
OOPS!! I forgot which forum I was in. I thought I was in the ho forum. I just realised I was in the General forum so I jumped over to the caboose and saw that you use lionel. Disregard what I said about the smoke oil making your tracks dirty. It will get oil on the tracks, but Lionel trains are so heavy that they will literally crush the oil and anything it attracts off of the rails. Your main problem with Lionel is probably going to be oxidation and possibly the lubrication in the locomotive gears drying out and getting stiff. With Lionel, you electrical pick up is from the rollers in the center of the locomotive that picks up power from the center rail. When you are looking for your problem, make sure the rollers are clean. The other thing I've seen on Lionel is that the arm that the rollers ride on is part of the electrical pick up and is insulated from the locomotive frame. There is a wire soldered to each arm that goes to one side of the motor. Sometimes the wires will break right next to the solder connection. You just need to strip back the insulation, use a little electrical compatible solder flux paste (rosen not acid) and resolder the wires.
