I experimented with some Nutiva RPO a couple of years ago.
Because I'd read a high percentage of RPO causes orange lather, I used 10% palm, which turned the batter quite yellow. I then split batter for a three-color swirl with charcoal, and red and yellow oxides. The palm turned the red oxide orange, okay because I scented with an orange-patchouli blend.
Here's the log before I cut it:
The orange color stayed true for 6-8 months as long as kept out of light, but then faded to a pale flesh color. The yellow was still strong, so if I ever do this again, I'd use more red oxide.