As has been said, hole size is critical.
If you don't need maximum strength, then you can make the hole slightly over size, which will make tapping far easier.

Spiral point/flute are good options for speed, but another option is a set of serial taps, which come as a set of 3 taps and you run them through the hole in order. Arc Euro sell them.

If you've not got anything like Trefolex, I'd prefer to use some general purpose grease rather than oil.