I know the 3400 in my sister's 05 impala was a tad on the noisy side all summer, (she bought it at the beginning of summer, and it had just been serviced at the local garage they normally use, not sure what oil he uses, but always uses carquest red filters, and before that it was always the local Chevy dealer)
I did an oil change on it a week ago, with the specified 4 qts of Dexos1 5w30 (AutoQuest - Meijer/Warren) ,and an XG3387.
She came down for a visit yesterday, and it was much quieter. almost unnoticeable.
forgot to check the oil level before starting the OC to see how low it was...