My oldest club is currently my Wilson hybrid which came with my package set going back about 3-4 years. It is never used though and I'm looking at replacing it with a 5-wood. Its days are numbered!
I've used the same Ping Pal 4 putter since 1996 - doubt I'll ever change it. Titleist DCI irons since 1997. Until recently was carrying 3 wood and 60deg wedge I bought in 1996/7 until upgrading both in January.
I've just gone back to my old 3 wood which is a cheap Big Ant 15 degree steel shaft (don't know the flex), nice deep face and I hit it straight 9 times out of 10. Wish I could find a 5 to go with it.
I have a 64 degree lob wedge that dates back to a Saab Invitation Day at The Buckinghamshire when I won it for Nearest the pin. Took me years to get used to it but now it's my favourite club in the bag.
The oldest in the bag is a V-Steel 7 wood around 10yrs old had it from new.
But my oldest club that will never go in the bag anymore is a PING putter from the early 60's. It even makes a ping sound when you hit the sweet spot. Had that from new to still has the original grip on.
With the exception of my driver, all my clubs are exactly the same age - got them in June 2010 after my bag got nicked. Broke my driver more recently and got a new one.
Everything in my bag has been replaced over the last 12 months and in a couple cases twice . brought a set of wilson irons before christmas and really didn't get on with them so just brought a set of pings