This is a controversial subject and bound to get some people really upset. I can only offer my thoughts having owned these vehicles and not intending to start a argument. I believe that just because you hear some noise is not any indication something bad is happening. These new engine blocks are made out of aluminum instead of cast iron. While aluminum is lighter weight, it also is not a quite as cast iron. Probably contributes to the noise resonating that would otherwise not be noticed in a cast iron block engine.
While there are some that contend there is engine damage going on, there are many more that have driven them for over 100,000 miles with the noise and not experienced any engine problem.
You also have to expect that owners will maintain vehicle differently. While some will use the better oils and filters etc as they can find, a great many more will always use the cheapest and often the lowest quality oils and filters. Yet they still expect the same longevity and good luck as the others. Often this is not the case.
My 2001 has made a light knocking (tapping) sound since around 15,000 miles (now over 40,000). It will often not make any noise or at least I never hear it. While I have not tried different brands of oil, I have tried 0W-30, 5W-30 and 10W-40 synthetic with no difference. I now am using 10W-30 and I since changing about 1000 miles ago, have not noticed any noise so far. Someone I know has a 1999 Silverado 5.3L and had this noise since it was new. Back then they tried it all and nothing stopped it so the dealer installed Mobil 1 and he has been driving all over the Great Lakes area ever since, only changing oil 1 every 6 months. Last time the subject came up was late last summer and he had nearly 150,000 miles and his engine had not been touched, noise was about the same, not any worse.
While I am not expert by any stretch of the imagination, I had a 1990 Lumina, a 1994 Lumina Z34 that had the very same noise. So its nothing new. The '94 I sold to a lady near me in 1997(she offered to buy it) and she drove it till 2001 logging over 100,000 miles as she told me and never had any engine problems, claims it was the best car she had.
We were discussing this topic of engine noise one day and a long time friend who has one of the few remaining full service gas stations has told me he hears engine noise all the time in a wide variety of cars and trucks. He even commented on which ones he though were the worst and I do recall it was Ford V6 and I4 engine in the Taurus, Focus like cars.
Would I buy another GM truck, in a heartbeat.
I better stop, probaly some are just dying to rant like me in the opposite direction.
