ORIGINAL: Harleypingman

Literally dozens of HDF'ers (myself included) have installed the HD oil temp gaugewith the sending unit mounted in the oil pan. There is a flush mount allen head plug next to the oil drain plug. Drain the oil, remove the plug and install an adapter: 3/8" male NPT X 1/8" female NPT; the oil temp sending unit screws into the adapter and the wiring from the sender runs along the lower right frame rail up to the front and into the fairing.

I moved the volt meter to the hole where the air temp gauge was and installed the oil temp gauge in its place so the oil temp gauge is below the oil pressure gauge. Very, very easy gauge swap.

Use the search function at the top of the page and you will find numerous threads on this easy DIY project.