I recently purchased a used 2001 Stratus RT. At first everything in the car worked fine but now as I try to get to first or second gear I have to floor it to get my car to move anywhere. Is this a sign of possible clutch slipping? And what kind of transmission fluid in a RT? Meaning what is the big difference between a GL-4 75W-90 and a GL-5 75W-90 gear oil?

 

Welcome to DF
The answer is yes, that is a sign the clutch is slipping.

 

I hope you didn't put gear oil in your trans.