Hi - I was on my way back from Flordia to Mich. this last weekend, when my 01 Lesabre trans started acting up about half way home. The car was loaded and running 75-80 mph when we came into stop and go traffic on a 85 deg day. Shortly after we got into the heavy traffic, I noticed the trans shifting hard and lurching forward from 1-2 and 2-3 gears. After about a mile, I pulled over, let the car cool for a half an hour and added a quart of trans oil ( it was full, but figured an extra qt. would not hurt it now). After that the car starting shifting better and now shifts like normal. I had changed the trans oil 2k before the trip. The car has 125k and I have only owned it for 2 months. Any ideas what happened and suggestions on what to expect or things I could do to extend it's life.