# A Question (or Four) For Duramax Owners



## thefulminator (Aug 8, 2007)

I'm looking at replacing my 1999 Silverado 1/2 ton 5.3L and would like to get some information on Duramax rigs.

What kind of mileage are you getting both with and without your TT?

What sort of additional maintanance does the Duramax take over a Vortec? For example, I understand that oil changes cost more but are less frequent with the Duramax.

Do you like or dislike your Duramax and why?

Do you think they are worth the extra cost?


----------



## Ray C (Apr 4, 2007)

I get about 20-22mpg on the highway just four of us in the truck and no payload that is about 65-70 mph. Towing I get about 16mpg that is with the truck and trailer loaded going about 60-65 mph up and down hills. As for any more maint. the fuel filter has to be changed more often then a gas. Is it worth the cost to get a duramax with the allison ABSOLUTELY !! I went from a 6.0 3/4 chevy crew to this and I love it. It tows great has more power then I will ever need. The allison does a great job with the downshifting with braking saves alot on your braking. When you get one you will never look back and say I should have got the gas.


----------



## ember (Jan 17, 2008)

We are on our 2nd Duramax with an Ali, and agree with everything Ray C said. We use it for towing not just the Abi-one, but also our equipment trailer, and you can't beat it!! The only thing you'll be disappointed with the Duramax is the lack of "rattle" !! IF you are looking for a loud diesel, then the Duramax isn't the truck for you!! BIL has a Ford, and DS has a Cummins and our Duramax whispers by comparison!!


----------



## 'Ohana (May 20, 2007)

Can't comment on the D-Max issue, however to add my $.02 I switched from gas to oil last year and it was one of the best decisions I ever made









Good luck in your quest

Ed


----------



## Joonbee (Jan 18, 2008)

Love our Dmax. Of course I am running out of engine goodies. But with the lift, bigger tires, front bumper, etc. We are seeing 16 as an avg. daily driving. Have seen 21 empty at 55-60mph and usually inthe 11-12 neighborhood towing our 5er. Towiing is night and day. Maintenance is alittle more $$, but as you said, not as often. So if you are considering a Dmax and have room in the budget. You will never regret it!!

Jim


----------



## nynethead (Sep 23, 2005)

i use mine as a daily driver, traffic highway and around town I average 17, was 19 before low sulfur came about.

I pull a 10K 5'er at 65 and average 12. when i had my 29Bhs i averaged 14 at 70. i've slowed down.

The only highway only mileage I clocked was coming home after dropping trailer off got 21 at 75mph.

and that was when the truck had only 5K. I know have 46K and I am still not sure if the engine has broken in yet....lol

I use AMS synthetic, 25K oil and filter but change every 5K miles, takes 10 quarts, fuel and ait filter every 15K

mechanic just charged me 40$ and I bought the filters myself.

Would never own a gasser again to pull a trailer. If I never intended to pull agaian then yes I would own a gasser.


----------



## thefulminator (Aug 8, 2007)

Thanks for the info. My truck has the first generation Vortec. It's a great engine but the mileage is really lacking. Around town I get at best 12.5 mpg empty. Pulling the 21RS from Lynnwood (North of Seattle) to central Oregon and back at 65 mph last week I averaged 8.8. The truck is pretty much stock with the exception of a K&N air filter. It just turned over 90K miles. I've had it into the local chevy dealer and they tell me that is pretty average milage for that year.

I have two growing boys and am going to need to upgrade to a crew pretty soon. Just looking into my options.


----------



## JMAC (Jul 31, 2009)

New member and my first post.









I have an 05 that I absolutley love. I have previously pulled a 16' enclosed trailer with two Harleys and am now pulling the new to me TT. Pulls great.

I use my truck for my daily driver and average 16-17 in town and 18-19 on highyway.

As the others have said, fuel filter would be a change from the gas burner... I also suggest changing the Allison spin on filter every 25K miles.

Cheers all.


----------



## phxbrit (Jul 24, 2007)

I get about 16-17 around town and about 19-20 empty on highways at 75 mph. I've gotten more on the highway, but those averages are including the times when the DPF kicks in, which will drop mpg down to about 12. Towing in the mountains with a 21rs, I get about 12-13.

I used to tow with a 99 f150 and it truely is night and day, particularly on hills and with headwinds.

I change the oil and filters myself so the cost isn't too bad. You'll want to change your fuel filter yourself at least once to be familiar with it, and carry a spare with you. I've been promised that there will be a time I will get a bad tank of fuel and need to change the fuel filter on the side of the road. Hasn't happened yet.


----------



## tdvffjohn (Mar 10, 2005)

Duramax in a Duelly with 410 gears.............normal city 12-13, highway 18-20...pulling the fiver..12........Love it!!!!


----------



## swanny (Oct 31, 2007)

I have on 07 gmc. I love it!!!!! I pull a 12k 5th wheel and i stay under 65mph. I got 12.5 mpg going to Florida. Just went to NY state with my boat and loaded got 20mpg. I don't really use it for anything else. lots of POWER and the ride when towing is very comfy. I've also noticed a big difference in filter prices so shop around. I use NAPA gold (WIX) little less then forty dollars. And yes the Dmax is very quiet.

GO FOR IT, Swanny


----------



## Silvrsled (Jul 24, 2008)

Wow, some of you are getting really good mileage. I get 12-13 towing our 21rs. In the mountains, I get about 10-11 towing. Normal everyday driving I average about 15-16 (city and hiway combined). I'm usually pretty light on the pedal too. 70mph unloaded and 62-63mph towing. I'd love to see 16 that Ray C gets. Any mods to your trucks?


----------



## swanny (Oct 31, 2007)

seems that's the way it is with the mpg. I also read the diesel place forum and the mpg seems to be all over the charts







For me I watch my RPMs i try to stay around 1700-1800 when i don't need any extra foot. My wife gave me some s*** last time out. we got passed by a swimming pool. yes I said a swimming pool on a flatbed. I just looked straight ahead and said, do we need to be in a hurry. she said A SWIMMING POOL. That's when a cd got put in the cd player.


----------



## N7OQ (Jun 10, 2006)

I love my Duramax, I will always have a oil burner from now on. I bought my truck in October and still don't have 3000 miles on it so it is no way broken in. I get around 14 mpg towing in the mountains, and about 16 around town. I have only driven it once on a trip without the trailer and got almost 18 mpg in the mountains and I was having fun and putting my foot into it. I think I will be able to easily get over 20mpg on the freeway with cruse control on.

Oil burners are the only way to tow and have fun doing it.


----------



## sydmeg1012 (Nov 10, 2008)

I am extremely happy with my 2007.5 LMM Duramax....only about 15k miles on it now, but getting 11-12 towing my TT (which runs around 9200-9300 loaded for camping), 16-17 around town and 20-21 on the highway. Straight stock, I'm not modding anything until after the warranty is up, and maybe not even then. Tons of power and torque, and that Ally trans is smooth as silk. The tow/haul mode is awesome when descending hills....tap the brakes and it takes over.

I do my own oil and fuel filter changes so that helps keep the maintenance cost low....we'll see how much it hurts when it's time for new brakes, belts, hoses, etc.


----------



## fourwalls (Sep 21, 2007)

Another vote for the dmax here. We have an 05 and love it. according to the reading on the dash we get 24 with the cruse set and running 55 empty and pulling the fiver we get 14. We will never return to a gasser and will have our secong dmax in a couple of years.


----------



## FlashG (Jun 23, 2007)

I have a 2008 Duramax/Allison 3500.

I have 7500 miles on the truck. The truck seems to be getting better mileage after 5000 miles.

I have been getting 14-15 mpg in town and around 20 mpg on freeway going 60 mph avg.

When we had the 10,000 lb fifth wheel we got 12 mpg on the freeway.


----------



## mswalt (Sep 14, 2004)

I've never really checked mine. I guess it really doesn't matter to me.....when it's empty I just fill up. I know I'm not trading the truck anyway so I just grin and bear it.

Mark


----------



## OutbackPM (Sep 14, 2005)

I bought a 2006 dmax with LLY tune but LBZ mechanicals which I use for everyday commute. Before I had a 2001 1500 Z71 with the 5.3 which I first towed the Outback with. The upgrade occured when the fuel differential went through the roof so it was more expensive unloaded to run than the 5.3. Now that prices have evened out its a little cheaper.

Towing is another story. Not only much easier but about 3-4 more mpg following the same route. Until you have towed similar loads with a gas then a diesel its hard to believe the difference in the experience. Pure hp numbers don't tell the difference.

What would I tell a future dmax owner?

1) You need more oil and you have a fuel filter to change. No big deal but if you drain it yourself change the drain plug for a fumoto valve so you can say fill one gallon jugs a time until the pan is empty. The fuel filter is easy to do but make sure you have the wrench for the plastic nut on the water sensor. Carry it in the truck along with a spare filter. Sometimes (not happened to me yet) you can get bad fuel that clogs the filter. 
2) Use a fuel additive. Mostly for the lubrication properties but I have noticed an improved mileage with both Stanadyne and the Optilube I currenly use. Biodiesel at 2% or greater also give you way more lubricity to protect the fuel system. This ultra low diesel has very poor properties compared to the high sulphur stuff of years ago.
3) Change the Allison spin on filter with the engine oil. Don't buy from a dealer ($45) buy from an Allison dealer($9).

4) Don't worry about cold starts because it starts as well as a gas but if cold say 30F and colder it burns alot of fuel in the warm up mode and all that oil and coolant does not heat up fast. Once warm its as good as any other time of the year.

I Have about 44000 miles on mine now and have just had my first issue with the drivers dooor turn 'arrow". It developed a short any blew a fuse. Not fixed it yet but unplugged it from the door so the others work OK. I've towed from Cincinnati to the easy coast twice and down to Disney with no issue to report. Generally I have been happy with the ride and the way it has worked for me so would recommend to someone else.

The last thing I will mention before you buy. If you bought it to tow the Outback(26RS in my case) watch out because it can tow an even bigger trailer than the Outback so destiney will lead you there( see my signature).

Good luck


----------

