Noisey Lifter

Hey guys I have a question. Yesterday I went out and started my 340 up and noticed that I have a noisey lifter and I mean Noisey but once the car idled for about 3-5 minutes it quieted down. The last couple times it did the same thing so I am thinking that I may have a weak lifter. I live in North Western Pa so with the cold weather my oil's viscosity is without a doubt pretty thick and could be the problem for the noisey lifter at the initial start. I have not torn the V covers off yet but am planning on doing that this week to see if I have a bad rocker arm pocket for the push rod which is not allowing the lifter to open. So my question is if I have to replace a lifter should I replace all or just the bad one? I was told that I should replace all along with the cam shaft and then I was told I need to check out all the lifters and if they all look good then just replace the bad one... Can you guys give me your opinon? Thanx