Hi,

In reading your post the part about having a twisted key is concerning but the California coldness comparison to other state side climates would have little to do with the internals of the locks tumblers per say.
In my opinion a twisted key hasn’t done the inserting slot channels in the lock any good.
So like you handle on the post old but goodly-worn could be the case at this point.

The pins in the cylinder have to pushed up their required amounts in order to rotate through other channels provided in the circumference of cylinder.
The vertical alignment is done from the sides of the insertion slot.

I would at least flatten the key straight a long time ago.
I have bent my keys before while still in my pockets from laying on my keys with more than just change in the pocket. A twisted key is from other forces and probably from our own doing.

Does a door lock or the trunk lock could have contributed but in my case I have several Volvos and I usually pick the wrong key or the wrong car was in my absentmindedness.
With that I try to be aware of how much pressure to put on the key.
A bent key is bad enough but a twisted one doesn’t do any good to the lock it got twisted in or those after it.
The continual use of it in, one lock over and over, will take its toll.

I suggest straightening the key or use another one altogether would be best.
You might try using some graphite powder blown into the lock to help minimize more tumbler and groove wear in the damaged cylinder.
The tumbler pins can shave loose fragments and those turn into rocks or a grit like substance that needs to move on down inside the lock. The graphite can help with all of that.
You can get in dry or wet formulations with the wet being more of an evaporating solvent if you suspect gummy gunk has entered into the scene a long the way.
Luckily on our 240s the cylinders have never been pointed upwards into the air to catch who know what, especially, cigarette ashes.
The new cars, with all the gadgets in the steering wheels, have issues that are lot more complex from human interaction too.

Hope this helps zero in on your problem and provide some guidance as to what you may be dealing with.

Phil