What oil for ballnuts?

I have the plumbing ready, 4mm nylon pipes to the nuts, but what do I squirt down them?

Tempted to use Castrol GTX, reasons...

1: I have lots
2: It is cheap
3: It is designed for high pressure bearings
4: It maintains the film even when cold
5: It's a bit gloopy so it won't escape too quick

Tempted to fit a perstaltic pump and program in a twist every hour or so, or is that being ridiculous :naughty:

I use Mobil Vactra on my lathe and mill. Be careful with motor oils as they can contain additives that corrode/erode bronze.