Here is the MSDS for WD 40, it's worth reading and researching the comoponants.
http://wd40.com/Brands/pdfs/msds-wd40_aerosol.us.pdf

It may not have actual kerosene or paraffin wax in it but those things are "kissin cousins" to what it does have.

For what little it's worth, my opinion (and that's all it is, an opinion) is that WD 40 has it's place and uses but a whole LOT of what circulates about it is BS. I don't think that it will hurt an engine but I'll no more spray it in one of mine than I'd use it as bait or a cure for arthritis.

Oh, and by the way, it was not made for the Navy. That's BS too. It was made for the Aerospace industry by a private company called Rocket Chemical Company and first used to protect the skin of an Atlas Missile. I certainly don't know how much, or even if, taxpayer money went into it and won't speculate about it either.