Why do they recommend not towing with a standard transmission ?

The clutch is the key here. Every time you release the clutch, it gets worn down just a little bit. Think of your brake pads. When you add more weight to to your vehicle, then it wears down even faster. Also, it adds just a little more stress to the transmission each time you release the clutch when you have additional weight to pull.

First of all, car with uniboby is not recommended for towing even the manual says it can. Manual transmission doesn't have low end torque like auto transmission does, when you shift the car jerks eventually the bottom rear end of your car will ripped apart, I've seen it happened.

Add on.

Even your car equipped with an automatic tranny, recreation towing is not recommended, especially bumpy off road, vibration will cause your hitch, trailer, bikes, gears and part of your car to come off, your car was designed for intermittent short trip towing.

(jpatton) its a manual, you don't have a tranny cooler...

Just for wear on the clutch. I'm not familiar with the Cobalt, but maybe it has a 'tall' first gear and would cause excessive wear on the clutch.

Usually because it's very hard on the clutch, and will wear it out very quickly. These days, even without the extra weight to get moving, they are marginal for longevity.

Good luck!

not equiped witrh tranny cooler and will burn out clutch