My 1997 lumina with a 3.1L engine has a lot of valve chatter, on start up it is really noticeable and when i have been running the car and put it in park. It must be a common problem because when my mechanic did the LIM gasket replacement they left a nut in the engine and ended up replacing the heads and it still chatters. I was thinking about using 30wt instead of a multi weight oil as i live in florida and dont see extreme heat or cold. how many of you have done that and does it sound any different? Also, i forgot to mention that i have a 2001 impala that makes the same sound so thats why im asking about 3.4's too.

Thanks for your input

i dont know if your motor has aluminium heads or not(but you do)(i hope)lol
but my 3.4 dohc is a little noisy(assuming the same prob)until it warms up,then she's fine.
no big deal
ive been driving it for the last year since i bought it,and no problems

More likely this is piston slap. it should go away in about 5 minutes or less, no?

They all do that. It's a combo of piston skirt slap when cold and roller lifter noise.

It will always sound like that. Doesn't hurt a thing....listen to any other one, you'll hear the same noises. They are just a clickety, rackety engine family. Used a lot of parts that don't come into full tolerances until they have some temp in them.

A real problem gets louder as the oil warms and flows better.

You'll probably notice when you first start it, for the first few seconds it's pretty quiet, then as it settles into idle speed, the noises begin.

Real problems will be loud as hell on initial start, calm somewhat as the oil pressure hits, then get louder again as the oil warms up and pressure/viscosity drop. If yours is typical of the breed, it's the opposite...starts quiet for a few seconds, begins to rattle as the idle settles down, then gets quieter the longer the engine runs...that's normal for these...