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Trucks and diesel fuel

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Dualie trucks

If you're pulling a fifth-wheel you're most likely driving a "dualie" pickup truck, so named due to the twin wheels on each end of the rear axle. Dualies provide much more stability than other pickups, which is very important when pulling a heavy load. In a dualie you won't even notice when a big-rig passes you on the highway. You will also want a diesel engine, which can better handle the wear and strain of pulling a fifth-wheel. Cumming engines are the best, and try to go for an Allison transmission if you can get it. A dualie will usually have a tow/haul button on the end of the gearshift arm. Be sure to push it in before you start driving with a fifth-wheel behind. There should also be a button on the shift arm that lets you set the gear ratio. I usually start off at a setting of 3, then 5, and then D, but experiment to find what suits you best. Go to a lower gear setting when pulling up hills, and they also work well to slow down the engine when going down hills. Fifth-wheel
-- definition
-- teflon disc
-- level ground
-- Cummings engine
-- Allison transmission
-- no DEF
-- don't need 4-wheel drive

Rest areas

-- When you pull into a rest stop, don't be shy about parking in the truck area. It's actually there for both big-rigs and RVs. Most stops will even let you overnight there. Don't detach, and try to be as quiet as possible at night. When we pull in we try to leave as early as possible in order to make room for the big-rigs.

Truck stops and service stations

Truck stops like Truck Stops of America (TSA) have become our favorite places to fuel up, for several reasons. We find that they are the cheapest and easiest places to fuel up for diesel. And since they cater to big rigs they also have plenty of room and are usually easy to navigate through. I have always found the staff helpful and they are used to dealing with newbies. The truckers themselves are usually friendly and willing to help; don't be afraid to ask questions.

If you're travelling on an interstate there will usually be big signs way ahead of the truck stop, giving you plenty of time to prepare for exit. They're normally located close to the interstate which is handy if you're getting low on fuel.

If you don't have a diesel tow vehicle or motorhome don't count on finding regular gas at most truck stops.

Places like Pilot (aka Flying J) and Loves stations also cater to big rigs and they have their own fuel discount cards, but we find that they are too expensive even with the discount.

If you decide to pull into a regular service station facility, look ahead to make sure that there is sufficient overhead clearance for your rig, and that there is plenty room for you to turn around or pull through. You really don't want to be put into the embarrassing position of trying to back up and negotiate around cars. Doing so also exponentially increases the danger of an accident.

Diesel fuel

If you have a diesel tow vehicle or motorhome, good news! There will normally lots of places to get diesel, especially on interstates. It has gotten to the point that only the smallest service station will be sans diesel. Even better news, the more remote the station is the more likely it will be to have diesel because diesel trucks are almost standard equipment for farmers and other rural folk.

Normal diesel fuel is also referred to as "diesel oil" or "diesel # 2".

Some truck stops label on-road diesel as "tractor fuel". Don't be confused by this - it doesn't mean it's for use in farm tractors; they're talking about the tractors that pull the big semi rigs. Tractor fuel is distinguished from the "reefer fuel" discussed below.

You will probably have to go in and pay first at a truck stop. The pumps do accept fuel credit cards but they are normally reserved for professional trucking companies. We have found some truck stops that accept regular credit cards at the pump, but they seem to be rare.

After you finish fueling, if you need to go inside to buy something, truck stop courtesy dictates that you pull forward enough for the truck behind you to use the pump. If you want to go in and eat, find an empty slot somewhere to park your rig.

Truck stops are also good places to stop and rest. If you fuel up there, most places won't mind if you park and catch a few winks.

Truck stop pumps usually have more than one type of diesel fuel. Make sure you DO NOT use what's called "reefer" fuel (see below). It's normally for farm use, and you can easily get into trouble with the police because reefer fuel has much lower taxes. And yes, they do monitor the pumps!

Here is a good little writeup on diesel fuel basics.

Reefer fuel

You only need to know one thing about so-called reefer fuel - don't use it! It is an off-road diesel product primarily intended for farm equipment. Although this type of fuel is available at truck stops, it should NOT be used for on-road vehicles like your tow vehicle or motorhome.

Reefer fuel gets its name as a shorthand for its use in refrigerated trailers, where it's used to power the A/C units that keep a refrigerated semi cold. It is also used in farm tractors and other machinery.

Reefer fuel is often confused with so-called "tractor fuel". Both are found at truck stop pumps. Unlike reefer fuel, tractor fuel is designed for use in the cabs (tractors) that pull big rig semis; hence the name. Unfortunately, the term tractor fuel sounds like it should be used in farm tractors, which often leads to confusion. If you're still confused at a truck stop, simply go in and ask the cashier. They are usually willing to help.

Reefer fuel is also called "red diesel" because it is contains a red dye to distinguish it from on-road diesel.

Note that while reefer fuel is cheaper than tractor fuel and will actually work in an ordinary diesel engine, it is quite illegal for use in semis and RVs because road taxes are not applied. Don't be tempted to get away with the cheaper reefer fuel - the cops love to hang around truck stops and watch for this! And yes, they can tell the difference by inserting a dip stick to see the red dye mentioned above.

Diesel Exhause Fluid
-- DEF

Umbilical cord

Tow trucks use an umbilical cord to connect between the truck and trailer. The cord provides power to the trailer's exterior lights and power brakes, and can also help keep a charge on the trailer's house battery. See here for a complete discussion of umbilical cords.

Attaching and detaching the trailer

Hooking up a trailer, especially one like a big fifth-wheel, can seem intimidating for a new owner. It turns out to be straightforward if you have religiously follow a step-by-step routine every time you hook up. See here for a detailed pre-flight checklist that we follow each and every time we set out and come back.

DO NOT, repeat, DO NOT let anyone distract you while attaching or detaching your rig. Serious and damaging accidents can occur due to distraction or carelessness. Put your phone away and don't be tempted to carry on a discussion with friends or relatives.


Here are a few things people have told us about that they said made their trips nicer. We don't personally have any of them but I thought I would pass them along.

  • Air-ride seats for the truck
  • Air cushion for the fifth-wheel
  • Heavy duty brakes for truck and trailer

If you have experience with any of these or other things you would like to let everyone know about, we encourage you to post a blurb on our forum.

In 2018 I kept getting a message on my 2008 Dodge RAM 3500 Cummings engine dualie: "Exhaust filter full. See dealer." I also suffered periodic reduction in power. I took the truck to my repair guy a couple times but couldn't make the message go away. I finally found a local shop that solved the problem. Originally I wanted to talk to them about chipping the truck but they told me that by doing what is called a "DPF delete" would solve the message problem while at the same time giving more power and fuel mileage at the same time. I took their advice and had the procedure done. It was expensive but I've not had to deal with the pesky message any more and the same time improved the mileage somewhat.

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