Almond Oil is awesome because its natural and it doesn't have the smell of baby oil and some less pleasant things.
https://www.amazon.com/solutions-Sweet-Almond-Moisturizing-ounce/dp/B0019LVFSU?th=1
But frankly, you can use vegetable oil too. It's thick and it's cheap.
You have to consider if you use a lot or if it stays on for a long time there could be staining, so I tend to trend towards darker apparel for this play, but it looks hot when lighter things get dark when wet so I sometimes do that.
The best way to get it out is to soak your tights/gear in lukewarm water and copious amounts of Dawn dish soap (the stuff they use to clean up wildlife after oil spills). Do that several rounds before you attempt any type of laundry in the washing machine, but in my experience it works pretty well. Or get in the shower with your gear on and use the dawn to clean the gear while you wear it.