I have a 1994 K1500 Suburban with 206.000 miles with the original 350 engine and 4L60E transmission. I just purchased a 2005 Cobalt for my daughter which is why I am on this forum, we have not received it yet, it should be in today or tomorrow. Anyways, I have owned a number of new GM cars, mostly Chevrolet (I am 41 years old, and the first of these was a 1981 Camaro Z28). I always follow the maintenance schedule to the letter. This schedule is created by the factory who knows the car and engine better than anyone. I change the oil and filter in my Suburban every 7500 miles (like the schedule says) and it still runs like the day it drove out of the dealer and still gets about the same gas mileage (11.7 mpg combinded city/highway). The recommendations of oil changes every 3000 miles usually come from companies that sell oil or oil changing services. The posts that explain the GM/Dealer relationship is correct. I own GM stock (doing awfully at the moment) and know something about their business. A dealer will purchase a car from the factory to resell it and make a profit, much like an auto parts store would purchase an intake manifold from Edelbrock to resell it and make a profit. The dealer also makes money on services (maintenance and repair) in addition to selling cars and selling financing. When a car is brought in for warranty maintenance, the dealer invoices the factory for that work. In my opinion, there is no real benefit to changing you oil sooner, or more often, but it doesn't hurt. If it gives you peace of mind, you should do it. By the way, this is a great forum, I am sure I will be visiting often.

 

I did my first oil change on my 2.2 base 5speed at 1940miles and it was pretty dark, a lot darker than I had expected for that low of mileage.

 

There is no way to judge oil condition strictly by color, especially since so many factors dramatically effect its appearance.

The only TRUE way to know whats going on in your crankcase is to have a smaple of your oil analyzed.