[JetSetWilly]

I don't think having the clutch down destroys the clutch, how would it do that? It is having the clutch partially engaged for a very long time that would destroy the clutch.

A clutch is destroyed by friction - slippage between the two plates that comprise it. This is a useful characteristic when pausing on a hill for a few seconds but I suppose there must be some people that keep the clutch partially engaged for a very long time.

But if you are sitting at a junction with the clutch entirely depressed for a long time the plates are disengaged and no damage is done. That's a bad habit for other reasons, such as if you get rear ended your car is still in gear and could then cause a further accident.

[Reason077]

That's right. Driving with the clutch partially engaged will wear it out. But having it fully engaged while the vehicle is stopped won't do any harm.

[jpindar]

It will wear out the throwout bearing.

[jessaustin]

Having driven manual pickup trucks for hundreds of thousands of miles, I'm sure this will happen eventually, but it hasn't yet...

[jpindar]

But do you hold the clutch in when stopped?

I generally don't. I too have driven several manual pickups, and only once had a squeaky throwout bearing. But I bought that one used so who knows what it had gone through before me.

[jessaustin]

I've never heard of this rule, and I suspect it's more valid for tiny European cars than for pickups. If I want to take off quickly, e.g. third in line at a short left turn, I keep the pedal depressed. If I'm tired, I'll shift out of gear. If neither of those conditions holds, I might shift or I might stay on the clutch.

[Unklejoe]

And crankshaft thrust bearings, which could ultimately lead to crank walk. It's more of an issue on high performance AWD cars which require extremely strong clutches. All of that clamping force (probably thousands of pounds) is essentially pushing the crankshaft "into" the engine.

Some engines are more susceptible to this than others.