Originally Posted by Dredd
some people say W-40 is just as good as actual "after-run oil" and some people use mavel mystery oil. I haven't tried either of these 2 products during after run maintenance so I cannot comment. I would assume WD-40 would work ok because the lubricants do not evaporate quickly and it drives moisture away from the area contacted which is a good thing. I do not know if it will cause any harm or not so do not take me to sound like I'm advocating it's use.
Some engines like Novarossi, JP. Sirio, they have silicone putty inside the crankshaft. WD40 and other petrolium products will damage the putty. Ex. the putty become swollen, or come off. Rubber O rings also don't like WD40. They become swollen too.
Only Nitro Fuel, Motor Spray ( Containts Non petrolium ---> Plastic Safe, ), and recommended After Run Oil can be use to clean engine's internals as my recommendation.