[Red Mustang Gt 46]

Hot = expansion
Cold = constriction
When the dealer filled the cooling system, I doubt if they "cycled" the system. Now that the car is in your hands now, fill the system with a 50/50 mix each time the car cools...do this about three times (meaning fill to line or top of reservoir). This removes air pockets within the system which makes your motor run a little hotter. When you park the car to cool, try to park it with the front end on an upward incline (let run for a minute or two), this forces any air pockets to travel to the reservoir.

In reference to the smell, probably the cap releasing antifreeze because of the pressure (doing what it's supposed to do) because of the added heat...

Hope this makes a little sense.

Cliff