Diesel or gas – it depends on your needs.

By Andy Thomson

It seems that most of the diesel trucks that you see for sale on dealer lots are rather expensive when they are suitably equipped for towing large fifth wheels. This brings up a very interesting question – do you really need to spend that much to have a nice truck for towing?

I often write in this column about the vehicles that we use to tow trailers – but it has been awhile since I wrote about our fifth wheel tow vehicles. Over the years, we have had a variety of gas and diesel trucks. Our current pickup is a Ram 2500 with the 5.7 Litre Hemi, 4.10:1 axle ratio and 5-speed automatic. People are often surprised that we do not have a diesel pickup in the dealership fleet, and they wonder if the Hemi could possibly have enough power to tow large fifth wheels.

Over the years, the big three have been in a diesel horsepower and torque race. This effort, combined with tightening emissions standards, has made diesels more expensive and less efficient. There is no denying, however, that they deliver massive amounts of RV towing power. The two determining factors for most RV enthusiasts who are debating whether to go gas or diesel are as follows: do they need the diesel power to pull a very large fifth wheel – or to negotiate mountainous terrain; and will they put on enough mileage to justify the initial cost of the vehicle.

Our pickup runs about 30,000 kilometers per year, with about 50% of that towing new trailers that are not carrying any loads – not even a tank of water, so for our purposes, not using a diesel is purely a financial decision. A diesel simply cannot save us enough in fuel to pay for the additional cost of purchasing the truck and maintaining it.

I am generally very positive about diesel power and regularly recommend the 3.0 Litre diesels in vehicles that are used to tow travel trailers it is just the current large truck diesels are so overkill for most RV owners needs that the numbers don’t always add up. Using current technology a 4.0 Litre diesel would be more than adequate for most of these trucks towing needs.

In the early ‘90s we sold large numbers of fifth wheels in the 12-16,000 pound weight range  – similar to today’s fifth wheels. Our most common tow vehicles at the time were trucks with 454 cubic inch gas engines or 6.5 Litre Turbo Diesels. The 454 produced 230 horsepower and 385 ft. lbs. of torque. The diesel had 215 HP and 440 ft. lbs. of torque. Both engines were mated to 4-speed automatics. Our customers towed with these trucks for years and went all over the continent. Although more power is always nice, these trucks certainly got the job done. If you compare these engines to the current gas engines that are offered by the big three, the torque numbers are equivalent but the new engines have far more horsepower. Just as important as the horsepower – the Ford and GM engines are mated to 6-speed transmissions the Dodge uses a 5-speed.

The Hemi we have does 0-100 KPH in 34 seconds while towing a 36’ Mobile Suite fifth wheel that weighs 15,000 pounds. This is quite respectable for this size of coach, and the truck is only 6 seconds slower than the V-10 Dodge that we had in 1999. Fuel economy is 2-4 MPG less than the current diesel trucks. Yes, it is a little slower on big hills, and it feels like it is working harder, but the bottom line is that the job gets done with very little trouble. As a solo vehicle the gas truck is more responsive to drive around town. The engine is lighter so the truck is more evenly balanced – that means that handling is better and it has a little more payload capacity. The gas truck does not have an exhaust brake like a diesel, but a gas engine can deliver substantial engine braking without one, especially the modern trucks with additional gear ratios. As with any combination, if you find that you need to ride the brakes all the way down a hill you are in too tall a gear and you need to shift down for additional engine braking.

The other way to save considerably on the purchase of a truck is to carefully analyze the model and options you select. Most of the trucks on the lots are either very plain work trucks or fully loaded ones with prestige level interiors – but there are some very nice models in-between. In a Ram, the SLT model with the décor package option does not have leather seats or a bunch of fancy gadgets, but it has power windows, locks, cruise, tilt wheel, tinted glass power seat, buckets, brake control, 4:10 gears and limited slip axle; really quite a nice ride. This is a great truck for the money. Ford has the LT model which is available with similar equipment GMC has the SLE, and Chev has the same truck called the LT model, again really nice trucks for a pretty reasonable cost.

All of these trucks are two-wheel drive, which for most people is all you need. If you are towing a fifth wheel the drive wheels have plenty of weight on them and traction is rarely a problem. Besides the original purchase cost, 4X4’s use more fuel and cost more to maintain. You could call a tow truck a couple of times a year and still be well ahead of the game financially, but you likely won’t need to. There are other advantages to a two-wheel drive as well. On a Ford or Dodge you sacrifice independent front suspension if you get 4×4, so the handling and ride both degrade substantially. Since the bulky straight axle has to clear the bottom of the engine, the truck has to sit taller which makes the centre of gravity higher and can cause clearance issues with the fifth wheel gooseneck. GM trucks keep their independent front suspension with four-wheel drive.

Where there is a case for 4×4 is for solo winter driving. When these trucks are empty the on snow traction could be better, but even then I would consider the limited slip axle option and put on a good set of snow tires. A few sand bags help as well. If you do get a 4×4 most of these trucks have a heavy-duty front suspension option, this is not necessary or advisable since the fifth wheel adds no weight to the front suspension.

Most of these trucks will have to be ordered from the factory to get the towing package and the options you require, as few dealers stock them this way, but I can certainly wait a few weeks to save $10-20,000. If you would like to get an idea of how these trucks perform, you are welcome to stop in and try out our Dodge, just call ahead to make sure that it is not on the road somewhere, picking up and delivering fifth wheels.


The post Outfitting a Fifth Wheel Tow Vehicle appeared first on RV Lifestyle Magazine.


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