Mausoleum of Mausolos will expire later, but how late?

[wieder]

I basically have two options for it. It now expires with explosives and that's not really too nice for those who play as commies.

I'll change the expiration to combustion or automobile. In order to build nukes you will need both of those. However if Mausolos would expire with automobile, it would be possible to build airplanes and take the war on the skies before the commie cities would become really vulnerable to spies.

I'll use combustion now but it can be changed if you can explain why.