My base model manual didn't have any transmission fluid come out at Thunderhill West and that was with the supercharger and brand new R1Rs (wish I had remembered to record it
). Most of the time I was in 3rd but I got down to about 3,200 RPM in 2nd gear on the tightest turn. I was nearly topping out in 3rd on both straights. Between the power my car is putting down and the mix of tight turns and long, higher speed turns at that track, I feel like the transmission would have been up to temp and had plenty of sloshing but I didn't have any leaks.
We towed two Goblins behind our base manual Cobalts to Tail of the Dragon last year. The Cobalts did a pretty good job most of the time but on long climbs we would have to drop down to 4th and sometimes 3rd to maintain highway speeds. There were times where would flat foot the poor Cobalts up mountains/tall hills for 3 to 5 minutes straight. They would turn 5,000 RPM for minutes. I'm thinking the weight of a Cobalt + the weight and drag of a Goblin behind it at 70mph going uphill for minutes is way more work for the transmission than you could ever do in a Goblin at the track with the stock motor.
All this makes me think your transmission might have been too full. If that is what caused it, at least it's good to know that the Cobalt has a self-leveling feature built into the transmission. Keep us updated.