2003 Buick Century

Good morning,

I will be travelling to Florida in February and I am hoping that this is not a expensive problem to fix. I have had this car for five years and it has never broken down. Once. I am hoping you can help me.

My question is as follows:

For several weeks now I have been experiencing some difficulty getting my car into gear particularly when cold. I place my car in forward gear (drive) and it seems to sit in a neutral kind of setting (out of gear) and a few minutes later it "pops" into gear with a loud "thud". It is very disconcerting. I was told by one mechanic that maybe I simply need to change my "tranny" fluid. I am hoping that is the case. What do you think? I could sure use your help.

Thanks.

Phil