I just took a trip the other day with my daughter and we noticed the truck was smoking on the highway when I stepped on the gas pedal, and did not when I was letting it coast. I pulled over and saw smoke from inside the engine bay and also saw transmisison fluid on the ground. After pulling over at a gas station close buy I assumed i may have a leak in a transmission line so puchased some fluid and added half a quart and got home (off the highway to be safe) with no concerns and checked the fluid levels with the dealer dipstick and it was not overfilled but saw nothing leaking under it the next day. a day later I took it about 10 miles into the city and saw smoke again from under the hood and I realized it was coming from the vent tube which is right next to the fill tube. I was told also by a local mechanic that without looking at it it could be but never gave me a reason why. question I have is the vent cap supposed to be lose and wiggle but still be unable to remove the cap or is it suppsed to be tight and not have any play in it? and could there be an issue with the cooling lines for the transmission that can cause the fluid to boil out the vent? This is sorta driving me crazy and need to know if its just the cap on the vent thats the issue. I am no expert at transmisisons, actually I know the least about them and I have heard the transmission fluid is under pressure and if the cap is lose the fluid will go there and out into the motor. Any ideas anyone?