SR and overheating

[DRG1]

I have had my car for about 3 weeks not and put in an aluminum radiator and electric fans. If the car sits over night and I start it in the morning, the temp automatically goes up a 1/4 way. and when i drive it for awhile it reaches the H. SOmeone told me that it really isn't overheating, and it seems that it's not when I pop the hood and look at the overflow tank. He also tol dme that since Japan Vs the US, they use either celcius or feirenheit (sp), so the my car reads in F, but the motor is actually reading in C. anyone ever heard of this? have any suggestions? TIA

Peter