just a humble opinion, use pure linseed oil if you want to season the pan, as most other vegetable oil does not season as well. make sure apply very very little. if you can see the oil, means too much already. make sure you have an oven that can heat up to 250C and smoke everything out. i normally do 2-3 coating (leave to cool overnight after heat treating it) before using it. remember to wash it with rough salt and hot/warm water after each use, and heat the pan up to dry and apply a layer of oil over it.

for me, unless you are cooking everyday with the cast iron, get a carbon or stainless steel...too much maintenance