The 06 FSM shows the auto and manual trans having different thermostats.
Manual opens at 169-174°F and is fully open at 194°F
Auto opens at 177-182°F and is fully open at 203°F

Anybody know why the manual gets a lower temp t-stat? Has there been any testing done showing the best temp for power vs gas mileage?
I feel my temps are way to high, It's not uncommon for me to see temps as high as 210° While cruising I generally see 195-199°

 

Lower temp for the manual? Perhaps Nissan feels the manuals will be driven harder and need to open the thermostat earlier to compensate. Just a guess.

BTW, 210° is no problem, your cooling system can handle a lot more. A 50/50 mix of coolant (ethylene glycol - commonly referred to as 'anti-freeze') and water boils at 265 deg. F and freezes at -34 deg. F (according to Prestone - who makes the stuff). This is with a 15 lb. radiator cap and cooling system in good condition.

Pressure in a cooling system raises the boiling point by about 2-3 degrees for every additional PSI in the system. The Infiniti 13 lb. radiator cap is 2 PSI less than the 15 lb. cap above, so the boiling point would be a bit lower - about 260 deg. F.

BTW, that pressure in the system is also the reason you don't remove a radiator cap when the engine is hot. If you remove the radiator cap from a really hot (e.g. 240 deg. F) cooling system the release of pressure will cause the coolant to instantly turn to steam that will burn you quite severely.

 

^^ Couldn't have said it any better myself.

 

Connect drain hose.2

Open radiator drain plug at bottom of radiator, and then remove radiator cap.3

Remove reservoir tank, as required, and drain engine coolant and clean reservoir tank before installing.4

Inspect drained engine coolant for contaminants such as rust, corrosion or discoloration.5

Remove air relief plug on radiator and flush cooling system with clean, drinkable water.6

Remove engine cover.7

Install reservoir tank if removed, and radiator drain plug.8

Inspect that each hose clamp has been firmly tightened.9

Remove air relief plug on radiator lefthand side.10

Fill radiator, and reservoir tank if removed, to specified level.11

When engine coolant overflows air relief hole on radiator, install air relief plug with new O-ring.12

Repeat step 10.13

Install radiator cap.14

Warm up engine until opening thermostat. Standard for warming-up time is approximately 10 minutes at 3,000 RPM. Inspect thermostat opening condition by touching radiator hose (lower) to see a flow of warm water.15

Stop engine and cool down to less than approximately 122°F.16

If required, fill radiator up to filler neck with engine coolant.17

Refill reservoir tank to "Max" level line with engine coolant.18

Repeat steps 13 through 17 two or more times with radiator cap installed until engine coolant level no longer drops.19

Inspect cooling system for leakage with engine running.20

Warm up engine, and inspect for sound of engine coolant flow while running engine from idle up to 3,000 RPM with heater temperature controller set at several position between "Cool" and "Warm".21

Repeat step 20 three times.22

If sound is heard, bleed air from cooling system by repeating step 11, and steps from 13 to 21 until engine coolant level no longer drops.23

Inspect that reservoir tank cap is tightened.