From the WD-40 MSDS . . .
3 - Composition/Information on Ingredients
Ingredient CAS # Weight Percent
Aliphatic Hydrocarbon 64742-47-8 45-50
Petroleum Base Oil 64742-58-1 <5
64742-53-6
64742-56-9
64742-65-0
LVP Aliphatic Hydrocarbon 64742-47-8 12-18
Carbon Dioxide 124-38-9 2-3
Non-Hazardous Ingredients Mixture <10
Not exactly sure what all that means, but if you search for Aliphatic Hydrocarbon 64742-47-8 you will find it as the primary ingredient of a zillion cleaners/solvents/thinners/etc. Looks like it's mostly solvent with a little oil and "good smell" added, with carbon dioxide as propellant.
I've always called it "aerosol kerosene".