Quenching in oil, how to?

Hey guys, I think I fell into the tool making rabbit hole.

Since I don't really want to spend 100+ euros and since it's not a common tool to find in thrift shops in my country, I have half of an idea of making myself a router plane with scraps of wood and an old file/chisel and a couple of hand screws.

I plan to bend the iron flat and parallel to the surface of the wood I'd be cutting so I would have a 30° bevel in order to attack with a nice angle the wood from any direction.

But since bending will likely require making the iron red hot, I believe hardening it back again is a must.

Therefore I searched a bit and I found that quenching is a crucial step into tool making. Lots of expert people do it with vegetable oil, but they never specify which one.

Do you guys have any experience?