normal to not upshift when cold?
I have an 06 g6 with just under 65k miles. It is the 4 cylinder base model. I've been noticing when it is cold out (-20 to 40 degrees Fahrenheit), the transmission will not shift into 4th gear (around 30mph). When the car has fully warmed up, and the temperature gauge is at the 1/3 mark, then it will shift into that next gear perfectly. No slipping or jerking occurs. It's weird because it seems like it will finally start shifting properly after the same amount of time and temperature reading each time. If I get up to 35-40mph, it will shift, but once I come to a stop, and only get back up to 30mph, it won't shift until warmed up. During the summer, I never experienced this problem.
I was wondering if this is a normal safety precaution the car has? I figure the car doesn't want to strain itself shifting back and fourth between the higher gears when cold, but I want to know if I'm wrong. My 96 Intrepid I have won't shift into overdrive until properly warmed up, and has always been that way without problems, so I assume this is a normal thing for cars?
I appreciate all feedback!