I'm going to install an old VDO analog oil temp gauge somewhere around the ashtray. My main question is where is the best place to get switched 12 v from? Thanks.

 

The cigarette lighter. My GoodBox gets power there.

 

Yeah, duh, so obvious, I don't know what I was thinking. Thanks though, and thanks for not making fun of me and just giving me a straight answer. I don't know what a GoodBox is, but I'm sure it's very good. And boxy. Edit: I looked it up, and I see it's a turbo'd swap kit. Nice. Another edit: Now I see another company that calls themselves GoodBox, and they sell a gizmo that turns your dash into a gauge readout. That must be what you're talking about. That looks kind of cool, how do you like it, and how much did it cost?

 

Yeah it's the gizmo, not the turbo thing. I absolutely love it, it's super convenient for troubleshooting or monitoring things at the track. Enthusiast cars should just have this from the factory. If you get a lead on a used one for an RX8, grab it. I paid $200 used.
Unfortunately, the manufacturer, who is a forum member here, isn't willing to produce any more until he has some number of pre-orders, and not enough people are willing to money up front on a thing that may or may not happen, so no new ones are being made.

There's a thread about it, you may have come across it. Originally designed by another forum member here.

 

You're probably going to have better luck building your own. Arduinos are actually pretty easy and the hardest part would be figuring out how to control the OEM display. Another option is to just output the data to a separate LCD. You could probably even have it output to an analog gauge that will accept 0v-5v.

I did this myself, actually. I used an Arduino, 20x4 LCD display and 3 sensors to get oil temp, oil pressure and fuel pressure. My next project is going to be adding a CAN-BUS shield to it so I can have it output data directly on the CAN for logging via my phone.