I was driving up my local ski mountain at night last week and when going downhill I was coasting along at 100k in 6th gear without pressing the throttle. The outside temp was about 9 degrees Celcius according to the 8's info display. But after about coasting for 2 mins, I started noticing my heat's not that warm anymore coming from the vents and whenI looked at my temp guage, it was starting to fall! So I gave it a little gas in 5th gear but it kept falling until it went all the way down to cold on the guage!!! I was semi worried so I slowed down and used the gas to acclerate again and when I got back to flat level highway and cruised for a bit there it came back up to normal. Anyone else had this happen??? Is it bad for the engine if the coolant/oil gets too cold while operating?? I used redline water wetter in my coolant so I guess that affects the coolant a bit. But I was wondering if I'd be left without heat in winter when it gets to -8 C here!

 

Hmmm.....
I don't think it should be doing that. How long does it take to warm up when you first start up from dead cold to go somewhere? If it takes a long time, I would bet on a stuck thermostat (stuck open or partially open). If it warms up normally (temp gauge movement within first mile, noticable heat from heater in 2 +/- miles) then I don't know, but something ain't right.

 

Regular start up it's ok takes about a min or 2 of driving before it reaches mid point.
but hmm so the temp guage in the 8's the coolant temp right? or engine bay or oil temp?
I remember reading a thread here last jan or feb someone having the same problem in really cold climates, they would cruise on the highway and their heat would slowly fade and the guage would go to cold while at speed. I tried searching for it but it doesn't turn up anymore

 

Sounds like you guys up NORT my need a different thermostat for winter driving?

 

but it never happened to any of the cars I've driven before!
weird...... I'm gonna bring it up at the next service....
first they boil my coffee in the cup holders and now they freeze me in winter! :p

 

I think this is the thread you were looking for. Seems like several folks had the same experience. http://www.rx8club.com/showthread.ph...ghlight=heater

Wish I knew how to copy that link in so I wouldn't have to type it all.

 

Thanks for the link!