I have a C6 transmission in my Bronco. It's got 215,000 on it. When I start up the Bronco after it sits all night I can shift into reverse fine, but when I shift to Drive it slips a lot before kicking in. In summer it only slips for a few seconds, but now when it is cold, it can slip for 10 seconds or more before going into drive. I also hear some clanking noises while it is slipping, but they are not too loud. It has enough fluid and the filter has been changed regularly.

This is something that I can put up with, but I would like to know if the transmission is failing. I would hate to have it go out on me while I am driving. In other words, is this a serious problem or just an annoyance? Thanks.