My 8.1L averages about 13mpg, have gotten as good as 15.5 on a trip from PHX to ABQ. running empty 65mph. With my Lance slide in camper at 65mph it sees about 11mpg. In the winter here they make us run oxygenated fuel so mileage drops on everything about 10%.
Just traded my '02 Suburban 3/4 ton 4x4 with an 8.1 for my '04 Silverado. I absolutely love the truck - but the Suburban was a very nice ride as well. The 8.1 was a real neck-jerker. As far as mileage goes, a solid 11mpg regardless of how I drove.
The only ongoing problem with the 8.1L was it burned oil from the showroom. The burning of oil really frustrated me and was one of my excuses to get rid of it. I baby all my vehicles and to know that I needed to check the oil on a brand new vehicle EVERYTIME I got gas made absolutely no sense to me whatsoever. Especially since the wife drove it regularly and she could hardly reach the dip stick. Supposedly, or so the dealer tells me, there is a TSB for the 8.1L's which clarifies the amount of oil they burn and mine was supposedly well within GM spec. Needless to say - I found "the" solution for it buring oil!
So beware on the 8.1L's for oil consumption. The dealer told me, and I quote, "GM specifies you may burn up to 1 quart of oil for every 100 gallons of fuel and still be within spec". With a 38 gallon tank (pushing 40 with the neck), I could be down 1/2 quart+ of oil at every fill-up.
I just traded in my 2002 GMC 2500HD 4wd with 24K+miles on it for my 04 Dmax. Love both of them. Miss some things about the gas. Like I knew more about the engine than diesels. Sure it ate oil and gas but man talk about power off the line. I could smoke the tires with the best of them. It will pull like a mule to.
with my 285's on it I'd get 13mpg empty with the cruise set at 75mph (the real 75mph not my gage) Pulling my 16ft parachute uh I mean Carson toy hauler (4000lbs) it would get 7-8 from Tucson to Phoenix (70-75mph) and 10mpg from Phoenix to Flagstaff in the mountains(50-65mph). When I get up there I'd be a quart low. Dam thing was a champ. I'd buy one if I end up moving away from the diesel. I've chatted with a bunch of 6.0 owners and they do fine till they hitch up to a trailer. If you don't tow then get the 6.0 if you tow any get the 8.1 the gas mileage isn't going to be a big hurt.
But beware the 8.1L eats more in rear tires than oil.
Blinky - Don't hold your breath on the Duramax in the 'burb/Yukon XL's. GM has been talking about it for 3 years now. Supposedly, it was going to happen for the '03 - it was a "sure thing". Then they said '04.... yeah, that's the ticket! NOT. I really hope they do, but i doubt they will - especially with the biggest competitor - the Excursion - being put out of its misery with a diesel option (well, they did breath another model year into it... but it is good as gone). The Excursion diesel was one incentive for GM to get thier act together from a competitive perspective - but this is no longer the case.
BTW - the last I was told by a GM employee was that the Duramax 6.6L engine was on "special provision" or some special wording like that, because of its high demand in the pick-ups. Not enough engines to go around in the pick-up world, let alone SUV.
I also heard - maybe even on this site somewhere (?), that there was a smaller "Duramax" being developed by Isuzu/GM that would be fitted for the GM SUV's. Has yet to be seen or confirmed.
my dad has an 03 8.1. He gets 10mpg (occasionally 11 or 12).What he has found that he likes is,when he"s pulling a heavy load it gets the no worse than 10mpg.The dealership still swears that asit breaks in and the valves seat his mpg shoud increase.I think he's nearing 11000mi on it .He enjoys the truck but is looking for areas to modify to increase mpg (without buying a diesel) Does anybody have any suggestions?
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