Thanks, Ron. It didn't occur to me to look up ASTM. But thats exactly the info I was looking for (and half expected to hear). Like I said, I really don't PLAN to drive it in that extreme, and as you pointed out, it wouldn't necessarily be that cold inside. I Just know I only want to recover the seats one time. And you never know; In this economy, what I am building to be a daily driver, could end up being an ONLY driver, cuz I'll sell the Ram before I sell the Challenger! Better fix that heater core after all LOL