Don’t worry, I’m also cost-effective (cheap). I picked up a bottle of Labelle medium oil for $5.49. It should last a long time. I believe it’s 5 oz but I’ll check and then edit my post. It’s a bit thin for gears, but seems fine for bearings and I do put some in the trucks because it’s all I had. I also used to to lube the crank pins/ side rods on my 2-8-0.
WD40 might not be a good lubricant…but it’s awesome as a degreaser. I used several cans of the stuff while cleaning up my MGB’s engine bay 
Last night I just put the shell back together without lubing anything. The engine runs fine for now, I just wanted to see if WD40 would work for future reference. If a good can of lube is only about $6 I think my budget can handle it. I’m even more confused after I posted this question than I was before. One reply says it’ll work fine then the next says that it will destroy my engine [%-)] Who’s right?
for future reference get labelle’s oils and grease, if you can’t get to a hobbyshop, get 3 in1, it’s sold in grocery stores, in a quick pinch, years ago I put vegtable oil on a tooth pick and dropped some on gears of an old loco. WD40 dries up too quickly to really lubricate.
It will not destroy your engine; it just won’t do it the good that your trouble is worth. As I said previously, it is a penetrant. It is a highly refined petroleum distillate that is a wonderful degreaser and oil cleaner-upper because it don’t got none in it…hence my statement.
If you would like to use it to free rusty bolts, or to get outdoor hinges working again, use it, but don’t expect it to also lubricate those rusty bolts. All it will do is get them working and protect them from rain for as long as it takes the volatiles to dissipate…about two days. A proper lubricant, on the other hand, has fewer volatiles of the type that escape quickly, and that is why greases and oils take so much longer to thicken, harden, and/or to disappear.
As Selector and I have stated, WD40 will NOT destroy your engine. It is not a lubricant as is Labelle, which is made FOR locomotives in our hobby. You CAN order this online, if you cannot drive to a local hobby store.
As I mentioned above, WD stands for Water Displacement.
I would go with any lightweight oil for sewing machines, razors, clippers etc.
The only thing i use WD40 for anymore is starting fluid for 2-stroke engines. If you have an outboard, chainsaw or snow thrower thats been sitting for a long time just shoot some in the carb and start it up. It seamed to gum-up whenever i’ve used it as a lubricant.
I was asked that same question today while working on our layout. Luckily, I said no because I saw this post this morning.
LOL, Opinions are like , well you know. WD40 will work fine until it destroyes your engine. As has been told to you, it’s not an oil. If you spray it where oil was it will find some and it’s solvent powers will redistribute the oil and thin it and it will seem like it has oiled your mechanism and fixed it right up. Then the WD40 will all evaporate and now you will be in worse shape than when you started. Like someone else said, the transmission dipstick on you parent’s car will have enough oil to oil maybe 50 locomotives on it. In a pinch a drop of vegetable oil, or cannola if youse on a diet, will get you by. But the right thing to do is buy some Labelle and do it right. Some things ain’t worth McGuyvering. Fred
If WD 40 can metl plastic, why doesn’t it melt the nozzle?
It could be that there is more than 1 kind of plastic. Fred