Due to a number of variables, it’s difficult to say precisely how much extra gas you need for a particular trip. Generally, 5 to 10 gallons is enough for most trips. That will get you to another source of fuel in most circumstances.
One factor is your vehicle’s mileage while off road. As a newer driver, you’re not likely to know that. Your first few trips should be on shorter routes close to civilization. These give you the chance to measure the difference in fuel consumption of your vehicle off-road. (And, of course, build some skills.)
Sizes, styles of gas cans
Rotopax Gas Cans RotopaX cans are rectangular and feature hand holds and openings that allow you to mount them in a variety of ways.
(Click picture for a larger image.) You have several styles and brands to choose from. In most cases, the style is dictated by how you plan to mount the gas can.
One well-known model is the “jerry” can (sometimes called NATO style). Wedco and Wavian make this type, in steel. The most common size is 20 liters, which easily holds 5 gallons. (Incidentally, the 5-liter just the right size for holding wine! But probably not food grade.)
The “jerry” can has been around since WWII. An important feature is the special cap. Note that it clasps securely, thereby eliminating leakage while you’re bouncing along on the trails.
The cans must now be sold with a unique funnel. With that special funnel the gas can is CARB compliant. CARB stands for California Air Resource Board. Look for the “CARB Compliant” label on all gas cans and spouts, even if you live in other states. The EPA has adopted the CARB requirement.
RotopaX cans are rectangular and feature hand holds and openings that allow you to mount them in a variety of ways. They come in smaller sizes than the Wedco cans, too. The 2 gallon version is very popular. The cans can be stacked together for easy transport.
Cam Cans , by Daystar, are designed to mount on the inside of the spare tire with the hardware provided. They are available in convenient 2-gallon versions. When you are first setting up your rig and need a quick solution, before you have had time to add tire racks and roof racks, look at the Cam Cans.
Another option is the fuel caddy by AEV. This is designed to mount between the spare tire and tail gate. A nifty arrangement, and at 10 gallons, it has a lot of capacity. The caddy is quite heavy with that amount of gas, so it stays mounted while you refuel. You’ll want to use something like a Super Siphon, described below, to transfer the gas to your tank.
You may have heard of or seen a Sceptor gas can. These are similar to jerry cans made of heavy plastic. They don’t have the CARB compliant cap and cannot be sold legally in the U.S. They are only available to the US military and Homeland Security.
A final option is to install another gas tank. That’s an expensive route, although a very nice solution for long range overlanding. Make sure the gas tank is installed properly and that your vehicle still meets air quality standards; that is your vehicle will still pass the Smog test.
You don’t always need that much extra gas while four wheeling, though. Four to ten gallons is usually plenty.
How to mount the gas can
Wedco Gas Cans Gas cans can also be transported on the top of your vehicle. This image shows six jerry gas cans on a roof rack.
(Click picture for a larger image.) The most common method involves mounting on an after-market bumper. Most replacement bumpers are designed to accommodate the spare tire and at least one 5 gallon gas can – many come with two slots for cans. RotopaX cans and AEV’s fuel caddy, as mentioned above, mount nicely to the spare wheel assembly. (Some extra hardware may be needed.)
Gas cans may also be transported on the top of your vehicle. The image shows six jerry gas cans on a roof rack. By far the largest drawback to roof top storage is lifting the cans into place. As a rule of thumb, you can assume Gas weighs about 6 pounds per gallon (depending on the blend and additives it can be a bit more or less). So a full 5 gallon can of gas is in the neighborhood of 30 pounds. Not too bad, until you have it overhead.
By the way, a gallon of water is 8.3 pounds, which explains why a 5 gallon can of water at 41.5 pounds is so much harder to lift onto the roof rack. Also you should use these calculations to determine the load you are placing on the roof rack. Six can at 30 pounds is 180 pounds which might actually exceed the rated capability!
I have a backup plan for the day, I feel too weak to muscle a gas of can onto the roof rack. I strategically placed the gas cans behind the sun roof so I can pop through and lift one up from the front seat!
Bumper rack This is a TJ bumper made by www.Nates4x4.com that holds 2 cans flat behind the spare tire.
How to safely fill and use gas cans
siphon Siphoning doesn’t require you suck gas!
Safety is paramount, even when you’re filling gas cans.
Static electricity is a real concern when working with fuel. Turn off your vehicle before filling. As you step out of your vehicle, touch some metal part of the car. Fill the gas can only when it’s on the ground.
Never smoke while filling. Turn off your engine and extinguish any flame that is nearby. Don’t transport gasoline inside a vehicle. The fumes can build up, overpowering the occupants and creating an explosive situation.
Make sure you use the proper color of gas can for fuels: red for gasoline, yellow for diesel and blue for water. The one drawback to Cam Cans is that they don’t come in red or yellow. Make sure you clearly mark which ones are used for fuel and which contain water.
Siphoning gasoline (and other fuels) used to be a challenge. Remember getting gas in your mouth? Well, times have changed. Safety Siphon and Super Jiggler have developed a nifty siphon that doesn’t require you to suck the gas. The siphon is simply a clear piece of plastic tube with a special brass valve on one end. After inserting the brass end in the source of fuel, you jiggle it a few times. That will get the fuel flowing. It’s like magic!
Both brands are relatively inexpensive, and they’ll drain a gas can in minutes. These siphons rely on gravity flow, so the gas can must be above the gas tank inlet.
Funnels work in a pinch but be careful to minimize spillage.
If you plan to store your gas for at least a month, add fuel stabilizer (STA-BIL or Motor Medic) to the fuel. Typical mix is 2 oz. for every 5 gallons of gas. Manufacturers claim it’ll last up to 1 year. I’ve had gas remain in good condition for upwards of 18 months.
Carrying extra gas is important for every 4WD trip. Use this information to help you determine which type and size(s) of gas cans are best for your vehicle and driving. You can then go four wheeling confident that you have some spare gas if your tank runs low.