Gauge is easy: 3 pins: one for gnd, one for sender, one for power.

How do I get a warning light to go on when there is low pressure/voltage? Searching has revealing absolutely nothing on this!

Id put a t-piece into the block and screw the sender and an seperate oil pressure switch into it. Run a wire from the switch to a light, and also a live to the light too.

You need a separate sender. A switch rather than a variable one.

You can get them in different ratings / pressures to suit your engine.

Basically wire from live, through a fuse, through the lamp, to the pressure switch, to earth (dependant on type).

Mike

But isn't the sender attached to the engine?

Yup, the sender is attached to the engine, which hopefully will be attached to the chassis, via an earth strap.

My set up goes roughly as follows:-

Engine - taping in the main oil gallery - short length of flexible pipe - tpiece - oil pressure sender on one side - oil pressure switch on the other side.

Oil temp sender is in the sump to try to avoid heat soak from the block.

HTH

Mike

Thanks very much, but for me those options are far too advanced.

I will go without one I think. I have the gauge already, so that'll do.

Oil pressure senders often have 2 terminals.

One goes to the gauge, the other is a switched earth for a low pressure light...

Music to my ears Stevebubs!! Thank you very much everyone.