Frank:

The first criteria is: Does the tank meet DOT regulations in all the US and Canada.  For example, if the tank is gravity fed to the main tank, as one key point, then it isn't legal for highway use.

ATA and Transfer-Flow tanks are "50 State Legal" -  and safe.  I don't know about the ones from Northern Tool / Tractor Supply, etc.  one way or another.  But some of those tanks are only "legal" off-road - i.e. on a farm for example.

Better quality, highway legal tanks are also baffled and pressure tested to meet DOT regulations.  Likewise an important factor.

This is a big deal if you were ever in an accident.  Not only as to safety but as to legal liability.  

That said, make sure anything you install is DOT legal.  They're probably more expensive - for a good reason.

Bill

Edited to add: Transfer Flow and others may still make a replacement tank for the OEM tank which could give you almost as much additional fuel as the 32 gallon aux tank you mentioned.  However, if I were doing it, and I have 3 times, I'd go with at least a 50 gallon tank which should fit under the cover.  Transfer Flow made one of those.  Haven't looked recently.  This isn't about how long one goes without stopping to use the rest room.  It's a convenience thing allowing one not to have to fill up everyday, go to a truck stop or bypass expensive fuel while not having "range anxiety."  

I am assuming in all this your truck is good GVWR / RAWR wise to carry any additional fuel with the 5er.  While that shouldn't be an issue with the Landmark I'd just make sure.

-- Edited by Bill and Linda on Friday 9th of November 2018 01:38:13 PM

Barb and Frank wrote:

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  Also, any ideas about where to get an auxiliary tank installed?  Any info is appreciated.

Frank

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 Frank: To answer this question which I should have done in the first place:

https://www.transferflow.com/installation

https://www.transferflow.com/shop/product/0800116625

Mine worked flawlessly for years.  Totally worth the price in Alaska and Canada alone. Saved a bunch of money and a "long walk."  5 gallons, which would have added only about 40 miles of towing, wouldn't have worked.  Not by a long shot.  Naturally, YMMV.  Get what works for you.  Just make sure its legal.

Bill 

Bill and Linda wrote:

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Frank:

The first criteria is: Does the tank meet DOT regulations in all the US and Canada.  For example, if the tank is gravity fed to the main tank, as one key point, then it isn't legal for highway use.

ATA and Transfer-Flow tanks are "50 State Legal" -  and safe.  I don't know about the ones from Northern Tool / Tractor Supply, etc.  one way or another.  But some of those tanks are only "legal" off-road - i.e. on a farm for example.

-- Edited by Bill and Linda on Friday 9th of November 2018 01:38:13 PM

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 Federal Motor Carrier Safety Regulations 393.65 (d) prohibits a system from supplying fuel by gravity directly to the carburetor or injectors.

If the auxiliary tank supplies fuel to the OEM fill tube it is legal to use. The "Diesel Install Kit for Auxiliary Fuel Tank" from Northern Tool contains a check valve to prevent over filling and feeds into the fill tube. This makes it legal to use on the road.

Cummins,

Thanks for the info - I thought the pricing on a replacement tank would be much higher.  This has opened up a new possibility.  I like the idea of saving the space in the truck bed for other things.  A 55 gallon tank should get us anywhere we want to go in a   single day.

Frank

RonC wrote:

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FWIW ... our travel days are typically 200 miles or less, so I rarely have to find fuel with the rig attached. I can see advantages to having extra capacity but for us, the expense and trouble just isn't worth it  ... to us ... YMMV.

-- Edited by RonC on Saturday 10th of November 2018 02:35:41 PM

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 + 1 

We try hard to keep it betwpeen 200-250 miles. With a 36 gallon tank ( an average of 10.2 mpg over the last 10,000 miles) we have plenty for the days trip. The only advantage I can see is making a good buy on diesel. But then one needs to factor in the extra money for the tank and what that adds to the costs per mile. But again, each to their own. 

-- Edited by Rickl on Saturday 10th of November 2018 05:38:04 PM

We have an aux fuel tank. Our experience using the extra fuel capacity has been very favorable, during the 4 1/2 years that we have been full timing. Due to family events and family care needs, we have needed to travel back to the northeast U.S. a number of times. Our travel patterns often have us traveling 800 to 1,000 miles between destinations. Often times we are traveling 2 or 3 days to cover this distance. Having the extra tank allows us to tow for 750 or 800 miles between fueling. We like to say that the extra fuel takes away one of the "variables" on travel days. With the size of our rig and truck, our only option for fueling is truck stops. With the higher cost, often lack of parking space, the need to prepay at many of the national truckstop chains, etc., we prefer to fuel up when we are not towing. Also, if we can travel for a couple of days without fueling, we can stay hitched up for overnight stops. Again, as Bill said, a lot depends on your travel style, and the excess capacity in your truck. For us, the aux fuel tank has made our lives easier. Ed

Call Tom at Classy Chassis. They are simply the best.

What Bill said on DOT certification. Concerning the recommendation to only carry a 5 gallon can…while that solves (maybe) the "I'm a little short on fuel" problem in the lower 48…even down here there are places where 40 more miles wouldn't really cut it.

The biggest. reason to have the aux tank IMO is cheaper fuel. Most 5vers who travel more than 225 miles or so in a day will not have sufficient range on a full tank for a complete travel day…which necessitates stopping for fuel…and since towing we're talking a truck stop (Loves, Pilot, etc) where you can take the rig around the back. Fuel at truck stops is way more per gallon…just this summer we've seen a 40 cent difference between big truck stops and what Gas Buddy found us in town that I could get the truck by itself into. When you're buying 70 gallons at a time…that's real money. Of course…some of the savings gets eaten up by driving the truck to the gas station…but what we typically do is figure out the optimum station to go to based on price and distance to maximize the savings then we just take the truck instead of the car on one of our trips out to the pub or something…then it's only the differential cost between the truck and car's cost per mile that's a factor.

Second biggest reason is that it allowed me to buy no fuel during our recent pass through of the Democratic People's Republic of Californiastan…we filled up in Carson City before we went to Fairfield at almost 40 cents less than non truck stop price in Fairfield and not again until we crossed the border into OR…which was cheaper than CA but not as good as Nevada was…there is no self service in OR so you have to pay for that $15 an hour minimum wage they voted in for the guy/gal that pumps your gas…although strangely enough you can pump your own diesel (but not gas) and you have to pump your own diesel or gas if it's in a bed aux tank…two different places told us that they weren't allowed to pump into aux tanks.

Barb and Frank wrote:

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Again, thanks for all of the suggestions. We ended up ordering an ATTA aux tank through Classy Chassis and will have it installed in our truck bed in a few short weeks.  Tom Martin was very helpful and great to work with.  Looking forward to not having to fill up at overpriced truck stops!

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 Can't say enough good things about Tom Martin and Classy.  

A suggestion as you have a Ram:  It costs a bit as it is a lot of labor - but - they can custom install the fuel gauge and on/off switch in the drivers door where the two cup holders are located.  It eliminates anything on the dash or in the center compartment.  Not a necessity but it looks really nice, is out of the way and the gauge lights work, etc. off the panel dimmers as well even with the door mount.  If you want this I'd let him know ahead of time as it does take more time and he'll want to allow for that as will you.

I've had two ATTA tanks Tom installed on two trucks.   It's a real nice installation IMO.

Bill

What Bill said about the switch and gauge. Tom does good work.