Essential for oil temperature reading is a sump plug adapter for your 1/8npt sender.

Ideal for the Honda S2000 F20C , Civic Type R K20 EP3 and the Mazda MX-5 NA /NB engine, this sump plug is designed to replace your existing M14 x 1.5 sump plug

Being a direct replacement, you can remove your existing sump plug and replace with this part and your 1/8 npt sender

Ensure you have a small amount of PTFE tape around the thread of the sender to ensure a successful seal