New oil pressure line

[Lastminuteracin]

Running the dash wiring and oil pressure line through the tub of the Anson this weekend. Do I need to prime the new oil pressure line?

[tlracer]

Not necessary - pressure will be the same right through whether it's full of oil or whether the gauge end has air in it.
As air is compressible and oil isn't (at least at the sort of levels we're at!), leaving air in the line might even give the gauge a slightly gentler life as it will damp out sudden changes.