I used both Rice Bran and Sunflower oil on my recent Black Iron (Carbon Steel) MB pan and they worked well.
However I did not like the actual frying method (with salt and potato skins) to season but much preferred the warming in a 200 degree oven, applying a ever so fine layer of oil, wiping it off, and returning the pan to the 200 degree oven, cranking it to 550 - leaving it for 2hours, then turning off and letting it cool down in the warm oven - left the best results hands down.