So I have been stuffing around with my cooling and just wanted some idea of what is to cold to run my FD at ATM I am have it running at 80-90 town 90c when feeding if all over town and on the highway over 80kph it flat lines at 74C, even when giving it some curry Oh and I am still on stock radiator

 

You're in Mackay QLD, yeah?
I'm down in Tassie

Basically it does vary between the FDs from all the evidence I've seen online. IIRC optimal running temp is around 95C, but dont quote me because its been a while since I looked in the service manuals..

I run 79-80C on highway cruise, at 100-110kmh. 90-95C during traffic, populated area driving. I've seen 100C on a hot day in traffic. And 15 minutes after shut off, the heat soak can bring temps up to 105C. Which is why I open the hood if I'm done driving and its hot. My car is stock, stock radiator (well, it has a manual core in it, with less fins per inch than the stock auto core, but only because I hit a kangaroo and damaged the original auto rad core and couldnt get another one)

74C seems very cool for highway driving- too cool. What body kit/frontal air scoops/intakes/etc do you have? The rest of the pattern seems normal enough.

You have a 2000 Series 8? Nice

 

no body kit just stock with lip. I dropped 2 dave's craig thermo switches in just wanted to make sure I am not ruining it to cold for the oil to do its job, the car came from japan with a 75c thermostat from what i can tell

 

It would be nice to see 80-85C as the minimum cruise temp. Especially in a Series 8.
Why did you add the Davies Craig gear to the car? What did you add specifically?

I would swap out the thermostat to a factory stock one if someone has changed it.
What mods have been done to the car in total?

 

Well the cooling system was stock as far as i can tell and I had a dead fan relay so I figured I would save a bit of time and pain and change to an adjustable Davies Craig set up, at the same time I changed the air intake to two Apollo K&N filters apart from that I only have a cat back. ATM I have speed two and 3 on the Davies Craig set to about 80 speed 2 and 95 speed 3

 

Sounds like it's running at thermostat temp as expected.

 

74 is too cold..... as mentioned above 85 is a nice number to see when cruising.

 

I have had a few thermostats fail in my time.

I've had one fail partially open. This caused the engine to run too cold whenever there was ample road speed. The car would get down to low 70's C if you cruised at any speed above 60kph in 4th or 5th gear for long enough.

I also had a thermostat fail sluggish. It would respond too slowly, you could see on the initial warm up the temperature would go above the correct temperature and then come back down slowly. It would hit 95-100 (on a 82C thermostat) even at really light load cruising at 80-100kph in top gear. Driving under load made it get hotter. This one was odd because after the initial warmup the car would not overheat anymore for the rest of the trip.

My thoughts? Buy a new Mazda thermostat.

 

Well thermostat is was working as intended someone put a 71c one in it....
Anyway it's back to oem now, however the car has worked up a case of the jitters when I plant my foot any input??

 

I have a 82/83C thermostat, I typically run around 85C cruising down to 80C depending on outside temps and I get up to 87-88C when outside temps are in the 70'sF. I am going to run some tests and see what I run at when its mid 80'sF outside soon.