You are correct, there have been no lubricated related failures I am aware of on a 3800 and indeed I know of very few on any platform. It is a rare thing indeed.
That said, Im going to take exception with the statement that as long as you change your oil, you'll be fine. PLEASE PLEASE dont take this as an attack, bash, or anything like that, its nothing more than just a friendly debate, so please dont let it become anything more than that.
You are correct in that if you change you're oil on a regular basis that you should be fine, but there are other factors that come into play more than just changing the oil on a regular basis.
1. City Driving
Your maintenance practices change drastically if you do nothing but short trip driving versus all highway driving. If you drive all city, stop and go, short trip driving then you are going to have to either change your oil more frequently or use a much more robust oil.
Short trip driving promotes condensation, thickening of the oil and rapid additive package depletion. Your Oxidation and Nitration will usually get pretty high on short order. Another issue is fuel dilution which thins out the oil in a hurry and drastically reduces motor oils ability to lubricate properly and maintain boundry layer protection.
As should be expected, if this remains unchecked or not dealt with it will most certainly result in significant wear increases and drastically shorter engine life.
Short trip driving is usually defined as driving less than 10 miles or not getting the fluids up to operating temperature for at least 15 continuous minutes.
2. Highway Driving
All highway driving is much easier on a motor oil and therefore you can actually extend your drain intervals out some, even on regular petroleum motor oil. As well it helps to minimize fuel dilution. If you have a fuel dilution issue and all you do is highway driving, you have a major issue.
It also gets the engine and fluids up to temperature for prolonged periods of time and therefore can evaporate any moisture or fuel that gets into the oil. What you have to watch out for more with all highway driving is the oils ability to sustain itself exposed to normal operating temps for sustained periods of time.
I have personally went 15,000 miles on my current Grand Prix without an oil or filter change. I used oil analysis to make sure the engine was doing okay, but I made it 15,000 miles before my LIM started leaking and I had to dial back the change intervals to combat the effects of the coolant getting into the oil. But because of the amount of highway driving I was doing at the time, coupled with the filtration I have, I was still able to manage 7 - 8000 mile drain intervals and I have the oil analysis results to show for it.
3. Infrequent driving
If you do not drive your car frequently, even if its for all highway or all city driving you still need to change the oil with some regularity. After you shut down the engine, moisture can develop and make its way into the oil where it reacts with combustion by products and starts to break down the oil and can even attack the metal surfaces. Your engine can actually rust from the inside. In this case, there just isnt any option other than to use really good filtration and to change the oil more frequently.
So while changing the oil on a regular basis is a good maintenance practice, a better option is to understand your driving conditions and selecting a motor oil that meets those particualar needs. My wife drives maybe 10 miles total a day. We live not a half mile from where she works. But even with that, undertanding that those conditions affected the engine differently than my 70 miles of driving a day allowed us to keep her car around for 12 years and right at 200,000 miles on it before it was deadlined and not because of an engine or tranny failure either.
There is more to motor oil and just changing it regularly. You have to understand which motor oil works best in your engine with your driving conditions and style. You could take two identical Grand Prixs that are the same in each and every respect down to how they are driven, how far, how often and so on and it is likely one particular motor oil will work really well in one engine and have lesser results in the other.
The goal of any maintenance program is to maximize engine life while minimizing maintenance costs. And just changing the oil on a regular consistent basis doesnt take that into consideration nor may it be the best approach for all situations.
