Help me understand the fuel economics of gasoline containers?

[Neverowneda4x4]

Sorry for the noob question.

So I'm having a debate with myself about mounting gas carriers to a bronco (or any off road vehicle). I feel like if I ever offroaded far enough away from the nearest gas station and ran out of gas, I'd probably be about 200-300 miles away. An emergency gas source (Jerry can or rotopax), with the mpg on these vehicles, at best I might get me 90 miles back towards home (two 3 gallon rotopax at 15mpg in an off-road environment) and still stranded. Am I missing something?

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[Brian_B]

I always kinda thought the same thing.

I guess the thought is ~only~ 90 miles is still 90 miles you aren’t hiking or waiting on someone to come get you. And for most people they are going to know when they hit Bingo and turn around - so running out of fuel would be a matter of just a few miles out, not stuck in the middle of Darkest Peru.

 

[SuperDave150]

I’ve done overlanding/off-roading in much of the western USA and I can’t really think of anywhere that is “200-300 miles away [from a gas station]”.

But more to your question, the idea is supposing that you’ve done the math and you’ll probably have enough to get out & back; the extra cans are peace of mind “just in case” your math is a little off.

 

[JohnnyBronco]

You don't have dual tanks like an 18 wheeler. You don't even have a sadle tank with built in reserve like a motorcycle so ot comes down to peace of mind when traveling close to max range from last fillup and knowing that the miles to empty on the dash may be 10-15% optimistic.

Are there any paved roads you travel Lin the dead of night where fuel stops are closed or beyond your range? That's a good time to have a reserve.

 

[SuperDave150]

Sorry for the noob question.

So I'm having a debate with myself about mounting gas carriers to a bronco (or any off road vehicle). I feel like if I ever offroaded far enough away from the nearest gas station and ran out of gas, I'd probably be about 200-300 miles away. An emergency gas source (Jerry can or rotopax), with the mpg on these vehicles, at best I might get me 90 miles back towards home (two 3 gallon rotopax at 15mpg in an off-road environment) and still stranded. Am I missing something?

It is worse than that even. From the Rotopax instructions: “we recommend venting your Rotopax at least once a day or every 10 degrees in temperature and every 1000 feet in elevation. However, depending on your location and usage, you may need to vent more than once a day, especially in areas with higher heat and elevations. …”

Gas cans leak. And need special care & feeding to vent.
Or you can do what a friend of mine did — screw that cap on hard & tight! Then his can burst from the expansion. And Rotopax wouldn’t warranty a replacement because he didn’t vent.

 

[Neps]

It is worse than that even. From the Rotopax instructions: “we recommend venting your Rotopax at least once a day or every 10 degrees in temperature and every 1000 feet in elevation. However, depending on your location and usage, you may need to vent more than once a day, especially in areas with higher heat and elevations. …”

Gas cans leak. And need special care & feeding to vent.
Or you can do what a friend of mine did — screw that cap on hard & tight! Then his can burst from the expansion. And Rotopax wouldn’t warranty a replacement because he didn’t vent.

Must be an issue with Rotopax, I've been carrying a Jerry Can on long trips for 40+ year and never had an issue and never had to do daily maintenance

My wife is a contractor and her crew carries multiple gas cans on multiple vehicles in the SoCal heat, covering an area from sea level to 4500' - never had an issue.

Most of the Rotopax-ed, traction board, high lift equipped vehicles I see in So Cal are for show and never see dirt. Best are the ones with 8 off-road lights on 38's with nary a scratch on the skids.

Regarding range, hopefully if you are any distance from rescue you'll not be alone and your group can combine supplies to get you out of trouble. Or you can do what we do, invite someone with a 4 banger Samurai - those little ***** can run all day on two gallons of gas

 

[Tricky Mike]

With a 2dr I have to be more range conscious. If I know 200 miles is a safe range on my tank, I don't plan anything deeper than 100 miles into nowhere and the couple gallons in the rotopax is just a safety factor. For example I was planning to do Elephant Hill in Moab. It's about 200 miles between gas up opportunities. I would probably have been fine, but the rotopax would make that more certain.

It is worse than that even. From the Rotopax instructions: “we recommend venting your Rotopax at least once a day or every 10 degrees in temperature and every 1000 feet in elevation. However, depending on your location and usage, you may need to vent more than once a day, especially in areas with higher heat and elevations. …”

Gas cans leak. And need special care & feeding to vent.
Or you can do what a friend of mine did — screw that cap on hard & tight! Then his can burst from the expansion. And Rotopax wouldn’t warranty a replacement because he didn’t vent.

I use a knockoff rotopax and have found once you burp it at the hottest temp it will just shrink a bit during cooler temps and you can leave it alone.

 

[raqball]

Sorry for the noob question.

So I'm having a debate with myself about mounting gas carriers to a bronco (or any off road vehicle). I feel like if I ever offroaded far enough away from the nearest gas station and ran out of gas, I'd probably be about 200-300 miles away. An emergency gas source (Jerry can or rotopax), with the mpg on these vehicles, at best I might get me 90 miles back towards home (two 3 gallon rotopax at 15mpg in an off-road environment) and still stranded. Am I missing something?

The 6 P's come to mind.. Prior Planning Prevents Piss Poor Performance.

Plan your trip in advance, including fuel stops, and adjust accordingly. Why would you travel 300 miles from anything full well knowing you don't have enough fuel?

I view the extra tanks as emergency use. Even the best laid plans faulter. Lets say you are on trail and it's unpassable due to downed trees, or whatever, and you need to divert. This diversion might burn up more gas than you planned. Heck you might need to divert more than once so now you've maybe burned a few extra gallons of gas you were counting on. That extra fuel tank you are carrying? Jackpot! Now you can replenish and make it to your planned in advance fuel stop..

 

[Neverowneda4x4]

I’ve done overlanding/off-roading in much of the western USA and I can’t really think of anywhere that is “200-300 miles away [from a gas station]”.

But more to your question, the idea is supposing that you’ve done the math and you’ll probably have enough to get out & back; the extra cans are peace of mind “just in case” your math is a little off.

Ah, thanks! I was starting to wonder if (or when) those people driving around the suburbs with rotopax mounted, ever use them.

 

[Neverowneda4x4]

The 6 P's come to mind.. Prior Planning Prevents Piss Poor Performance.

Plan your trip in advance, including fuel stops, and adjust accordingly. Why would you travel 300 miles from anything full well knowing you don't have enough fuel?

I view the extra tanks as emergency use. Even the best laid plans faulter. Lets say you are on trail and it's unpassable due to downed trees, or whatever, and you need to divert. This diversion might burn up more gas than you planned. Heck you might need to divert more than once so now you've maybe burned a few extra gallons of gas you were counting on. That extra fuel tank you are carrying? Jackpot! Now you can replenish and make it to your planned in advance fuel stop..

I guess that was the internal debate I was having (admittedly, as a total noob). Of course my answer was "I would never do that, so when would I ever use gas cans?" Which made me question the usefulness of them (or if they were just a fomo/ GAS thing). But yours and a lot of the other's answers make perfect sense. Thanks to all for the explanations!

 

[Brian_B]

I was out to dinner with my boss - got to drive him around in my Bronco.

He sees a couple of jeeps in the parking lot - all pristine condition, with full overlanding setup. He asks “What are those red tanks for - they don’t look big enough to carry much gas”

I said “They are just there for show”

 

[Neverowneda4x4]

You don't have dual tanks like an 18 wheeler. You don't even have a sadle tank with built in reserve like a motorcycle so ot comes down to peace of mind when traveling close to max range from last fillup and knowing that the miles to empty on the dash may be 10-15% optimistic.

Are there any paved roads you travel Lin the dead of night where fuel stops are closed or beyond your range? That's a good time to have a reserve.

Fortunately, I do not

 

[Oldhippie]

My CJ2a had 10 gallon tank…it would not make it from “last gas“ through rubicon or “Mojave“ to “next gas” with out A “Jerry” can…16 gallons on my 2dr is “marginal” if any thing goes south…plus have ya ever poked a hole in your tank?? And Normal road mpg means nothing off road…

 

[JohnnyBronco]

Ah, thanks! I was starting to wonder if (or when) those people driving around the suburbs with rotopax mounted, ever use them.

Or have anything in them but air

 

[Bugkillah]

Aren’t the cans more for trailered dedicated off-roading vehicles, and the extra gas is to just get you back to the trail head???

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