I have an 2018 Nissan Titan XD with the Cummins 5.0 V8 diesel. I bought a 40 gallon aux tank and install kit. When filling up, do u normally fill the factory tank first and then the aux tank? Also, what mileage do you think I will get when towing. Local driving I get about 17 mpg and solo on interstate about 22.I was thinking I would average about 13 towing on mostly interstates but a friend said I would probably do better.Also,someone else suggested I look into after market chips/tuners. What do you think?

I can’t comment on the aux tank, but as far as towing mileage, that will depend on the trailer, conditions, and driving style

I have an aux tank on my RAM. I fill the OEM tank first, then the aux tank. But it really won't make much of a difference.So many variable for towing MPG, don't even know where to start. The biggest variable is going to be your speed. You will get your best MPG around 55 MPH. I can't drive that slow, but some can.

Doesn't matter which you fill first. Tuner sounds like fun. Idk much about the 5.0 engines, but emissions in tact tuners get it around 350/600 which is a real nice pulling motor! Don't do it for fuel mileage though. Won't really hurt but likely won't help. Won't help your warranty with but you know that.

22 mpg is pretty good. I have not heard anyone pulling that kind of mpg. A friend of mine can only get 17 mpg highway.

My best is 22.5 highway empty but usually over 21, winter blend drops it to 20. 17 - 18 around town mpg.

Nissan Titan XD aux tank | Good Sam Community

12 Replies

gregrc75
Explorer
Jan 31, 2019
RGar974417 wrote:
gregrc75 wrote:
I have a 2016 Titan XD and I get 23 mpg highway in the summer.
When towing my 7500 lb trailer I get 11.5-12 mpg. I have not beat 12 mpg towing yet. I have 31,000 miles on my truck now.
Our trailer is about 1500 lbs lighter so that might help a little. Plus you have 2 Labs, we only have one, a black one. That should help too. Haha

You know, I did notice a drop in mileage when we got the second lab! Hahaha
RGar974417
Explorer
Jan 31, 2019
gregrc75 wrote:
I have a 2016 Titan XD and I get 23 mpg highway in the summer.
When towing my 7500 lb trailer I get 11.5-12 mpg. I have not beat 12 mpg towing yet. I have 31,000 miles on my truck now.
Our trailer is about 1500 lbs lighter so that might help a little. Plus you have 2 Labs, we only have one, a black one. That should help too. Haha
librty02
Explorer
Jan 31, 2019
I would be more worried about the payload I am losing especially when towing adding that 278 lbs of diesel fuel to the truck...
gregrc75
Explorer
Jan 30, 2019
I have a 2016 Titan XD and I get 23 mpg highway in the summer.
When towing my 7500 lb trailer I get 11.5-12 mpg. I have not beat 12 mpg towing yet. I have 31,000 miles on my truck now.
RGar974417
Explorer
Jan 30, 2019
APT wrote:
Budget and plan for 10mpg. If you get 11-12mpg you will be happy. If you budget for 13mpg and get 11mpg, you are not likely to be pleased. Set up your mind for success.

I had a Titan with the gas motor and I got 9.5mpg with that. Solo driving with the diesel I know I am getting about 4mpg better with the diesel than with the gas so that's where I came up with 13. I guess we'll see.
LanceRKeys
Explorer
Jan 29, 2019
I fill factory first then auxiliary, seems like I get a gallon or two more that way as the foam in the main tank settles out and gets filled while the aux is filling up.
APT
Explorer
Jan 29, 2019
Budget and plan for 10mpg. If you get 11-12mpg you will be happy. If you budget for 13mpg and get 11mpg, you are not likely to be pleased. Set up your mind for success.
demiles
Explorer
Jan 29, 2019
My best is 22.5 highway empty but usually over 21, winter blend drops it to 20. 17 - 18 around town mpg.
ksss
Explorer
Jan 29, 2019
22 mpg is pretty good. I have not heard anyone pulling that kind of mpg. A friend of mine can only get 17 mpg highway.
Grit_dog
Navigator
Jan 29, 2019
Doesn't matter which you fill first.
Tuner sounds like fun. Idk much about the 5.0 engines, but emissions in tact tuners get it around 350/600 which is a real nice pulling motor! Don't do it for fuel mileage though. Won't really hurt but likely won't help. Won't help your warranty with but you know that.