Best place to route mechanical oil temp capillary through firewall

There is a hole which the speedometer cable passes through. Plenty of room for this,

Do you really need a mechanical oil temp gauge inside the passenger compartment? Why not use an electronic gauge and make your life easier?

Thanks guys. David, I just like them, I like the 270 degree sweep and their accuracy.
Making my life easier is something I suck at.

I run a mechanical oil pressure gauge.  runs from the back of the block through the firewall hole the throttle cable uses and up the center spine

This has always been my thought for decades concerning mechanical oil pressure gauges; you're having a wonderful time, driving on the limit through the twists and turns and then, suddenly, the line leading to  your mechanical oil pressure gauge breaks, spraying hot 50 psi oil onto your pants (or legs, if you're wearing shorts). No thanks, don't need any surprises like that.

Mike Mileski

Tucson, AZ

Mike, mechanical oil temperature and pressure gauges don't actually have oil inside the capillary tube that goes into the gauge. It's actually full of ether gas or liquid. If you break the line, all that happens is the gas escapes or you might see a bit of white fluid.

I guess I'm still stuck in the old school world. I had a hot rod back in the 70s that actually had a tiny hollow copper tube that led to the mechanical oil gauge in the dash. I changed it to an electrical gauge for the very reason I mentioned. Thanks for educating me.

Mike Mileski

Tucson, AZ

You are correct on temperature gauges but oil pressure gauges have an oil line connected to them and if broken will spray hot oil.

Mike Mileski

Tucson, AZ

My gauges are VDO.  I installed a mechanical oil pressure gauge.  I run the plastic capillary tubing which does carry real oil from the fitting at the back of the block.  Never had a problem with it but yes, I guess if it somehow breaks, hot oil would definitely come out.  I would be more concerned frankly with the heater hoses failing next to my feet and burning me with 200 degree water and hence why Lance List replaced my aging rubber hoses with stainless braided lines.

I probably should replace the plastic VDO tubing with copper for piece of mind.

I'd run this stuff if I was running pressure:

that stuff looks nice.  what's the source on it?  thanks

It's just -4AN line and fittings.
You have to adapt the 1/8NPT (I think) to AN at both ends.

Jegs, Summit, has some kits, in various lengths:
https://www.jegs.com/i/JEGS/555/41059/10002/-1