It's good to ask questions first like this. Otherwise you could get dissapointed. Valve wear on any engine essentially is normal. Nothing that man builds lasts forever. First and foremost if your truck isn't setting a missfire code, there would be nothing for a technician to really go and look for. The missfire detection designed into that vehicle is IMO "The Best In The World" for a production vehicle. Hence one of the reasons the light can come on so easily.

Trying to come up with an excuse to have them look at the truck, is essentially automotive-hypochondria (I made that up can I claim it? :),,,) Even a complete teardown, without associated symptoms would yeild no actual trouble found, and work being done that would not produce any net results. Well outside of the fact that there is always a chance to introduce a symptom from the service that either isn't present now, or in fact is present but so far gone un-noticed by you only to be readily apparent after the teardown which then get's incorrectly blamed on the teardown.... Ah do you follow that thought?

An example of what I am talking about was recently observed by my Brother-In-Law and he called me up to laugh about it. I've often talked about the "I never noticed it before you" syndrome. My Sister's Subaru had a brake warning lamp flashin on and off. When he called I told him to check the brake fluid. But he said, she is also talking about something clicking under the dash ever since that light started blinking. Sure enough, I nailed the low fluid level, and he pulled the wheels and checked the brake pads. It's going to need linings pretty soon. The clicking noise? That's the solenoid that releases the gear shift lever when the brake is applied. She simply never noticed the sound until the brake light flashing made her pay closer attention.

Dollars to Doughnuts, I'll expect the same thing could easily happen with your truck if you have this looked at prematurely. The techs could end up in a no-win situation. Please don't get me wrong with what I am saying here, it easily might not be the case with you personally, but I have seen it so many times in my career that it is a trend that the public has to be made aware of, so that they take a step back and see why some of the consumer complaints really occur. GM to their credit has identified what they feel is an abnormal trait. They are extending the warranty in the event something does not meet their expectations, and customers needs. Applaud them for it, and "IF" your vehicle developes the problem inside of this contract they have made with you, rest assured they will live up to that agreement. You also have entered into a contract with them, that they have willingly altered in your favor. Be fair with them. Don't ask for something if you really do not need it. JMHO..

john g,
Thanks, it is always good to read your expertise in a well written, thoughtful response. I didn't know anything about the fact that the GM has a sophisticated misfire detector. That given, I have no reason to wonder if the truck has a low level misfire that I can't feel yet.

This Chevy is my first Chevy since my 1969 Chevelle, and before that a 1949. In fact the Chevy is my first US built car since my 1980 Sunbird. I have driven many US made cars via AVIS, and have found them to have improved in quality, and for the 2005 Colorado, I haven't had to take it back to the dealer for warranty repair in just over two years of ownership. So, its initial quality is on a par with the Japanese cars/trucks I've owned in the previous 25 years. I still have two Japanese products, a 1999 Mazda and a 2004 Subaru, both good machines so far. I believe the Mazda was built in Japan, the Subaru Forester X25 may have been built in the US.

I had a pair of 2.8 L V6 GM engines a long time ago: One was a 1980 and the other a 1983. I suppose that your engine is much newer and design changes most likely has happened, but the basic design of that engine has endured over the years - it is a good one except for intake manifold loosening and leaking and this can be repaired by a shade tree mechanic taking care and time. (Larger displacment versions of that design were built in later years.)

For what its worth, my engines had ADJUSTABLE hydraulic valve train. Getting proper adjustment with the engine shut down is almost impossible due to leak-down of the hydarulic lifters. It's a little messy, but the adjustment can be made on this engine while running at ldle with the valve cover removed. Spread some catch cloths/paper towels around the open valve cover land. Be careful not to get these (and yourself) caught in the drive belts. Loosen the adjuster until it just begins to make a tapping noise, then tighten the adjusting nut per the amount stated in the repair manual. The amount that I remember was three turns - but I am quoting from memeory so it is best to verify this value. According to the manual, this procedure adjustes the piston of the hydraulic lifter to the middle of the lifter barrel.

The ajusting nuts were of the self locking type with a plastic friction band rolled into the top of the nut. These are very easy to use.

My engines were fairly smooth running when in good condition. I did damage the no. 1 cylinder in the 1980 engine before I caught on to what was going wrong. The intake manifold was leaking. When it got bad enough to leak coolant into the oil pan, it became obvious that it needed new gaskets.

The intake manifold on my wife's 1983 failed quickly while she was comming home from work. It dumped about 2 quarts of coolant into the oil pan in a matter of minutes. You could hear the crank throws slosing in the fluid (LOL).

While looking for used cars, I have seen that engine with 150,000 miles on it and still running surprisingly well.

Both the 2.8L and 3.5L are new in-line GM engines, a 4 cylinder (yes, a very large displacement for a 4) and a 5 cylinder. I'm not sure when these engines first hit the market, 2005 may have been the first year, maybe it was a year or two earlier. In any case, there is probably no connection with the V6 engines you mention. Good to read, however, that those engines held up well. I like to read that about US products.