This week I took my 2017 ATS 3.6 Premium Performance to the dealer for its regular service and asked them to investigate a transmission shudder. I have been having the typical "rumble strip" sensation upon light acceleration at moderate speed (20-45 mph) intermittently but fairly consistently most of the summer. I did notice it happens more often on warm days, and the day of my service was unseasonably cool. They called late in the day to say they could not duplicate it. My service advisor is very good and was aware of the bulletin, and told me when she broke the news and saw my dismay that I should bring it back the next time it does it and let her or her boss ride with me while I duplicated it, which I thought was reasonable. Today (a Saturday when they are not open for service) was a warm day and I could make it do it almost at will.Hopefully we get some warm days next week so I can demonstrate it for them. Since the car only has a bit more than 6000 miles on it I want this fixed ASAP and am hoping the new fluid outlined in the bulletin will do that.