Hello hello, k I'll try and make this very brief. My 03 Z has had overheating problems for the longest and have been through at least 3 radiators a lot of thermostats (Thank you Nissan dealerships).
This past summer my car started overheating again after not even driving it for a mile and to top in off I'm stationed in Germany so when and if I do take it to a Nissan dealer in Germany; they look at the car like "WTF"? (350Z's are not too common around here)
A guy I know told me to get a Mishimoto low temp thermostat. Got it, installed it and BAM!!! Car doesn't overheat!!! Problem now is, it works a bit too good. Now the car won't warm up to operating temps and the only way it will is if I drive it pretty hard. Yeah it might work wonders when I'm on the autobahn and can drive 120mph+ but I very seldom do that cause gas ain't cheap!!!
Any advice? Thanks in advance.

 

I guess my question is will this do harm to the engine. I know my Z has a habit of overheating in the past but at the same time I'm thinking longevity.

 

I have a mishimoto thermo too. But. I'm in south Mississippi. Where it is 70 degrees in December. My car has no trouble getting up to operating temp, but on to your question.

I am not an expert nor do I claim to be.

But I think you're good. How hot is it getting? (1/2 way warm, which is average, or like 1/4 warm?)
Even on cold mornings, if I crank my car about 5 minutes before I drive it, when I get in, it's good to go.

 

It only gets about 1/8th of the way warm. Then when I start driving it, it kind of drops down a bit. I've been reading around and some say that running too cold, it would only effect the gas mileage and other say that it would ruin the longevity of the car.

 

I dont know about the Zs block and cooling passageway design, but I know from working on certain outboards that the thermostats are critical because when gutted the cylinders receive uneven cooling, which causes the cylinders to distort slightly resulting in accelerated and uneven wear over time. People just assume, hey the more cooling the better. Not so. Ok for the racers, but for regular running not adviseable.

Also reminds me of the discussion around thermostatic/non-thermostatic oil cooler sandwich adapters. The point being you want to get the oil to operating temp asap, and with a cooler that can take a while if you dont have a thermostatic valve on the adapter to keep it closed until the oil gets to operating temp.

Especially since you are in a cold climate, your oil and water are probably never getting to full operating temperature, which is worse than the above because thats akin to running a cold motor.

Does your AC ever blow hot air, or does it stay cold even at full hot?

Does your oil pressure normalize or stay high similar to when you cold start it?