pull the carpet back on the passenger side and see if it's wet.

 

Nope. It does not seem to be. What's next?

 

Well. I can only speak from experience on this. My 87 renix was losing coolant too and I could not figure it out to save my life. Turns out that when it got all hot there was a micro crack in my pressure bottle that was leaking. Now I know yours is not renix but the same thing could be happening with hoses and maybe even the overflow bottle?

 

Gosh, I'm going to have to try and locate a leak I guess.

 

Hope I m wrong I couldnt see any leak either till I measured how much oil came out when i did change it looking at it you couldnt tell ,my head had a hair line break between clyinder 3&4 could barely see it when hot.good luck