Ignition tumbler
 

Just noticed the other day that the kind of hard to turn the ignition key. Then I have tryied the key on the pasanger door and it was impossible to unlock the door. The trunk is operating as it supposed to do.
I have tryied then thevalet key and it works good a on all locks.
Is the conclusion that the master key may be worn-out?
I have noticed that a lot of posts here advise to change the cilinder lock before it gets stuck completely.Whay should I do?

I have noticed that a lot of posts here advise to change the cilinder lock before it gets stuck completely.Whay should I do?
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How about changing the cylinder lock NOW?

rad,

Because the passenger lock is typically the least used, and therefore, the least worn, I think your assumption that the key is worn is a good one. However, why not just order a new switch tumbler by VIN, because a new key comes with it anyway? At least that's how I've always seen them.

If a new key works fine, then you probably just need to get a new master key for your car. I agree with the comment about the passenger door lock.

If you start to have intermittant problems turning the ignition with a good key, then you want to head over to the dealer/shop soon, and if it is at all safe (i.e. unlikely to result in your car being stolen), to leave the key turned halfway in the ignition. Removing the tumbler requires the key to be in the ignition, and turned to one of the positions. Without this, you have to drill out the center of the tumbler...