The active ingredient is ..... LANOLIN! Yup, sheep grease. It is terrific for dried out, cracked skin! It does "dry out", but VERY slowly, and once the liquid solvent/carrier in it evaporates, dust and dirt stick to it very little. That's why it is ideal for PTO splines. Or anywhere else you want a "dry" lubricant. The lanolin is semi-solid at room temp, which is why it requires a lot of can shaking to work right.
For the rubber door seals, etc. on your vehicle, better to use "Sil-Glyde" silicone grease from NAPA. You can get a big tube (like 8oz) that is a lifetime supply for <$10.