Here is what the 2000 model year owner's manual says about the hour meter:

3000 miles, 100 hours normal use or 50 hours severe use - Change oil and filter, Perform A service.

6000 miles, 200 hours normal use or 100 hours severe use - Change oil and filter, Perform A and B service.

9000 miles, 300 hours normal use or 150 hours severs use - Change oil and filter, Perform A, B and C service.

The pattern goes on, but I am not going to copy the whole thing unless someone really needs it.

Personally, I figure that my usage of the Hummer is about half "normal" use and half "severe" use so I usually try and do the oil changes around 75 hours. Through a paraphrasing of comments made to me in the past, there are some people who think that me operating any vehicle, at any time, creates a new usage category called "catastrophic use". Oh well, they don't have as much fun as I do.

I have several freinds that average 10 mph with their off road trucks. That 10mph is alot harder use than the 45mph my truck averages(I don't spend near as much time off road as they do). It would be almost impossible to determine this without an hour meter. That means if they wait for 3000 mile oil changes like I do, their trucks would have run 4.5 times as long as mine. It takes me approximately 67 hours to go 3000 miles, if my freinds waited for 3000 miles that means they would wait until they had 300 hours on their trucks under more severe conditions. If you spend enough time off road, & you want to protect your 50,000 dollar plus truck an hour meter doesn't sound like such a bad idea to me.