First trip with the 3.0L Duramax

swervin36 · July 15, 2020

I usually make a trip from Colorado to Alabama in March-April to do some fishing and help my mother do some stuff around the house. This year I had to wait till July due to everything going on. To say the least I was very pleased with how the truck performed on the trip. I like to take the southern route cutting down through New Mexico and picking up I-40 in Amarillo. Last year I made the same trip in a 18 Crew Cab 4wd Sierra with a 5.3. For that trip the MPG going out was about 18-21. On the return after passing Oklahoma City, I had a head wind and best the truck would do was about 16. With the Baby Duramax the trip average was 22-24. I was easily able to go over 500 miles between fillups. With a little prior planning I was also able to find diesel between 1.99-2.09 a gal. Total trip was 3100 miles and DEF usage was 2.5 gal.

TNTSierra · July 15, 2020

I have read nothing but good things about this motor. I think GM hit a home run on this motor. Really glad they took their time on it, did lots of research, and built it from the ground up. Unlike what Furd did with their diesel and just brought it over from Land Rover. Congrats on the truck MPG's.

deepsouth · July 15, 2020

What was your best millage when going thru the mostly flat interstate driving? I would have thought that with all those highway miles your average would have been better.

War_robinson · July 15, 2020

The MPG does no do well over 70 mpg. If I stay between 50-65 mph I can maintain 26-28 mpg ( with leveling kit and 285/65/18 toyo open country tires).

swervin36 · July 16, 2020

12 hours ago, deepsouth said:

What was your best millage when going thru the mostly flat interstate driving? I would have thought that with all those highway miles your average would have been better.

Me too. I was expecting closer to 27-30 for the trip. Especially after passing Ok City on the trip out. Now I do have a lead foot and had the cruise set at 80 for most of the trip. If I had kept it at 75 or below that would have probably gotten me into the 27 range. Still pretty impressed with the mileage I did get. I have also made a few trips to Denver and seen a 30 mpg average.

tonto340 · July 16, 2020

I have made one trip in my 20 Silverado with the 3L diesel. From south of the Roanoke area in Virginia to the Baltimore area in Maryland on I-81, I-66, I-495 and I-95 I averaged 29 mpg (hand calculated) with a few speed runs to 95mph. The trip was 325 miles.

SkiDooNick700 · July 17, 2020

21 hours ago, swervin36 said:

Me too. I was expecting closer to 27-30 for the trip. Especially after passing Ok City on the trip out. Now I do have a lead foot and had the cruise set at 80 for most of the trip. If I had kept it at 75 or below that would have probably gotten me into the 27 range. Still pretty impressed with the mileage I did get. I have also made a few trips to Denver and seen a 30 mpg average.

Every time I see a 3.0 post that says low to mid lows on highway, I'm always disappointed to hear, then I find out that was at or near 80mph. Now that is impressive MPG at that speed. My 6.2 would be a couple mpg off its highway rating too if I kept it around 80.

The fact that you can do 80 in a truck and comfortably get over 20mpg is impressive - especially with your leveling kit and tires.

Phatty · July 18, 2020

Note the cruise control setting. I had just exited freeway. These trucks are ridiculous.

Duramax3oh · July 27, 2020

On 7/16/2020 at 12:09 AM, swervin36 said:

Me too. I was expecting closer to 27-30 for the trip. Especially after passing Ok City on the trip out. Now I do have a lead foot and had the cruise set at 80 for most of the trip. If I had kept it at 75 or below that would have probably gotten me into the 27 range. Still pretty impressed with the mileage I did get. I have also made a few trips to Denver and seen a 30 mpg average.

Nice. My wife drove the truck on our last trip back home. She has a lead foot and was absolutely screaming down the highway. I thought for sure a trooper would bust her but luckily not. Definitely 80+ with a heavy foot. I just looked at the DIC for the 280 miles after reset and it shows 24 mpg which I was pleasantly surprised by. Little city majority highway all flat land

gf2020 · July 29, 2020

Just got my RST 3.0 last week and already have nearly 500 miles. First lengthy drive was all highway from Mass to Maine on Monday, cruise control set at 7 over, so 72 or 77 MPH depending. Trip computer showed 25.6 MPG, which I thought was pretty good for a brand new engine but I topped it off and hand calculated was even better: 249 miles / 9.2 gallons = 27 MPG.

tonto340 · July 29, 2020

I recently completed two more trips from SW Virginia to Maryland and got 28 and 29 MPG. I'm satisfied with that.

Duramax3oh · July 29, 2020

9 hours ago, gf2020 said:

Just got my RST 3.0 last week and already have nearly 500 miles. First lengthy drive was all highway from Mass to Maine on Monday, cruise control set at 7 over, so 72 or 77 MPH depending. Trip computer showed 25.6 MPG, which I thought was pretty good for a brand new engine but I topped it off and hand calculated was even better: 249 miles / 9.2 gallons = 27 MPG.

Awesome! Welcome to the 3.0 family. I don't hand calculate often, but everytime I do it has been better than what the DIC indicates. Not staggering by any means but a little higher which is great

redwngr · July 30, 2020

2 hours ago, Duramax3oh said:

Awesome! Welcome to the 3.0 family. I don't hand calculate often, but everytime I do it has been better than what the DIC indicates. Not staggering by any means but a little higher which is great

I've noticed that from many of those that have reported DIC vs hand calc for the 3.0L.

swervin36 · July 30, 2020

4 hours ago, Duramax3oh said:

Awesome! Welcome to the 3.0 family. I don't hand calculate often, but everytime I do it has been better than what the DIC indicates. Not staggering by any means but a little higher which is great

It was the opposite with my 18 5.3. The DIC always showed about .5 - 1 mile better than the hand cal.

mikedege · July 30, 2020

I just went on a 500 mile round trip, and averaged 26.4 for the whole trip in my 3.0L 4x4, with 5 peeps in the truck and cruise set on 79mph most of the time.

I was pretty happy, my last 2015 6.2L 4x4 averaged between 21-22 mph to the same destination. Very happy with the baby D-max!!!

Mike