RE: nitro
WD-40 is perfectly fine in the engines........I have used it many many many many times over the years, as well I have recommended hundreds of people use it to clean their OWB when it is slipping....Nothing cleans a gummed up OWB better then WD-40.......... Now the thing with WD-40 is you need to let the solvent dissipate before you fire the engine.... The solvent reacts badly and will kill your glowplug violently if you try to start it "wet" ......I usually recommend people give it 5 minutes for the solvent to dissipate before starting the engine....