8-9mpg towing and 11-12mpg non towing. Best I have ever seen is 12.5mpg on a long higway run, relatively flat. Burns about a quart of dino-oil every 3K. Going to try synthetic to cut that down.

luv to see this.... thanx

With Sydways permission I will post them here...

I have a 2001 GMC w/8.1. Dually approaching 200K miles and it runs great. I have changed the oil every 3000k, and used Amsoil in the trans. have pulled numerous 38 ft plus boats throught the mountains in Tennesse, no problem.

Its a good motor/trans Package.

Your mpg figures are exactly what I got out of the 97 I had. A thought about your oil consumption. Mine was burning oil when it was new. Took it in and found out why. The a holes at the factory forgot to install the valve seals!

Try a synthetic, that should help. But also, you may want to consider going with a slightly heavier oil too. Such as switching from a 5w-30 to a 5w-40 or 10w-40. With the synthetics, its much easier to get away with this due to fact that they flow so much better, it shouldn't hurt any fuel economy, along with helping consumption.

I switched mine to 20-50 v twin, the same as I run in my boat and the oil consumption stopped. there is slight piston slap in them at start up, but with the heavier oil it is all but gone now as well.

All my vehicles has 100% synthetic fluids, transmission, axles, engine.... Bak in my racing days we did some testing and I have since run synthetic in everything except my outboards oil/gas mix. I just took the head off a 2003 Audi with 40K miles on it that had run on cheap oil - very expensive as all the cam bearings are toast. Synthetic oil = the best insurance possible for your rig!

I posted the pics here:

http://www.offshoreonly.com/forums/s...ad.php?t=78812


It does work, but unless you set it up absolutely perfectly; it will diminish your surge brake actuator's movement, and effectiveness.

Well, the Yukon XL popped up today and the guy delivering it made 16MPG from NM to NV doing 80MPH with cruise control on. The truck is awesome and got every bell and whistle you can get on the truck. It is a one owner and it looks beatiful and the brakes are no comparison to the beefed up High performance brakes I had on my 97 Suburban. I will tow the boat to the lake tomorrow and see how it works for what it is intended to do. The mexican air condition system above the windows is comming off and there will be some wheel upgrades in the near future. It also got the numbers in the glove box that I wanted.... G80, GT5.......

Looks good too: