Thinking about buying wood posts? Stop, Wizard Time.

Regular Wizard visitors know the routine - if it is not a long term product; DO NOT BUY IT! Such is exactly the case with wood posts, especially 4" x 4"s (which are actually 3 1/2" x 3 1/2"). The Fence Wizard will not go out of his way to poop on a wood post, if the post is already there and its convenient - then maybe.
The point is- wood posts are a short term product. Are they cheap? Yes. But wood posts on any type of privacy fence will last little more than 8-12 years with new records coming in daily on the short side. Today's Cedar and Redwood posts are from younger trees and less dense to be sure.
Here comes the whining - "But Mr. Wizard, I was careful to buy only pressure treated wood posts". The only thing The Wizard hates more than garbage is glorified garbage. If you are building a wood picket fence of any type - The wizard commands the use of a galvanized steel post. If you want quality spend a little extra and use "Postmaster Steel Posts" . You will not need any brackets to attach your rails (Use three rails of Douglas Fir 2" x 4"s). If you just can't afford the $24-25 each for the Postmaster Posts then go with a 2 3/8" (O.D.) 16 Gauge. The round post will require brackets and a cap so you will not save much and will get much thinner steel.
If your vinyl fence kit requires wood inserts or posts - be careful. Remember that when moisture, dirt, and wood combine - the wood will return to the earth as nature intended.
If someone puts a gun to your head and makes you install a wood post - make certain that you build up the concrete base above the surrounding dirt level - then cone it off so moisture falls down away from the base of the post. Then ask the gunman if he/she is happy.