Two types of coconut oil are our favorites; both food-grade, one form is semi-solid, available in tubes - this transports easily in KK's purse. The other form is fractionated coconut oil, sometimes known as MCT.
Both forms are excellent; natural, mostly hypoallergenic, soap and water soluble, non-staining, and edible. They are taste-neutral, and won't harm silicone toys or non-latex condoms. The semi-solid form melts at skin temperature, forming a silky liquid. MCT is already liquid, with similar properties - it warms to skin temperature rapidly. We've found them to be "just right" in terms of lubricity - not too thin, not too thick.