N62 4.8is thermostat swap from 105 to 90c problem

[bmwktm]

Hi, two years ago i swapped OEM to 90c thermostat because i was getting "thermostat stuck" error and was not able to reach temps over 70c. I have decided to give it a go with custom 90c so i can keep the pressure down. It is 17 y/o car so just trying to prevent coolant leak problems. Now my temps are just fine, around 85-90c, but I am still getting same error message because the car expects temps well over 100c.

Everything is working properly and i have no problem with that. BUT i think it is consuming more fuel since DME thinks the engine is still cold and it is throwing more fuel in it, hence lower MPGs.

Also I do not know if there are any other problems i could have in several years because i want to drive this car as long as i can since i like it really much.

MY MAIN QUESTION:
I have been trying to find out for several months now, is there a way to code 90c instead of 105c using INPA, ISTA or NSCexpert/dummy?

Anyone switched to 90c? What was your experience with these problems and how did you solve them?

Thanks!