Not the oil in your crankcase, the stuff in your bathroom cupboard. Even the most natural of moisturizers and skin care products have multiple ingredients, some which I can't even pronounce. Read the labels of your lotions and potions, your lip balm and conditioner, and see for yourself. Of course, just because I can't pronounce it doesn't mean that it's necessarily bad for you, but I prefer simple, basic things. The more ingredients something has, the less I want to use it. My choice for personal care is coconut oil. It has one ingredient: coconut.
Pure coconut oil, also known as coconut butter (not to be confused with cocoa butter, from the cacao bean) is one of the best all around moisturizers that I've ever used. It's usually available in health food stores in either refined (for cooking, usually) and unrefined (still has a coconut-y smell) styles. I like the Spectrum brand, but Nutiva also has a super high-quality organic oil. Virgin coconut oil is made from fresh, not dried coconuts, and I always choose the expeller-pressed unrefined version.
Coconut oil makes a superb lip balm and sunburn treatment, and works well for dry skin and hair. It's also an excellent intimate lubricant (though it may not be safe for use with condoms). The oil is solid when the temperature is under 76° F, and a liquid when it's warmer.
For use as a hair conditioner, work the oil into your hair, down to the roots, about a half an hour before showering. Shampoo as usual, but skip the conditioner. It's the only thing I use for hair moisturizing, and I think it works better than shampooing and then adding conditioner afterward. If you still need conditioner after the oil treatment, you might look into getting a milder shampoo.
As a food, it's a great substitute for butter, and the refined version has a high smoke-point of about 450° F, which makes for a great sauté or stir-fry oil. Use coconut oil instead of your usual choice for baked goods, and you'll end up with a super-rich dessert (and the coconut flavor is hardly noticeable).
If it's time to change your oil, try coconut oil and leave the unpronounceable ingredients alone.