Does anyone here have a
"pre-oiler" installed in their airplane?

It would seem so logical, yet I've never met anyone with one installed

I have one on my Glasair Experimental. It is a Moroso (performance auto) unit.
It acomplishes 3 things. Pre-oil and pre-pressurize engine oil system 3 quart
capacity, Stabilized oil pressure (steady pressure), will maintain oil pressure
for the prop durring aerobatics.