I live in northern Minnesota and am looking for a pickup truck that can deal with the winter cold and still be cheap to drive. Not having much experience with diesels, I’m interested in your opinion about an older diesel’s suitability for both me and where I live. I’ve read about ex-military diesel pickups and SUVS being sold dirt cheap in vehicle auctions all around the country. Some have fewer than 5,000 miles on the odometer. Are these vehicles worth considering?
Can the ex-military pickups be a good choice for a fuel economy vehicle? What should I look for when evaluating one of these diesels at an auction site?
Is the 6.2L diesel a good choice for our cold winter climate? Does diesel fuel still gel or clog the fuel systems when it’s really cold? Is the block heater still the only way to go for open-air parking during the winter?
My father owned a Pontiac wagon in the late 1970s that was converted to use a 6.2L diesel (was originally equipped with a 5.7L diesel). That car would deliver more than 30 mpg on a good day, and was a great car out on the open road.
Vadan Wiess Via Email Aside from being bare-bones transportation with few amenities, most ex-military 6.2L diesel pickups and SUVS are geared lower (usually 4.10) and come with a 3-speed non-overdrive automatic transmission. The low differential gearing combined with no overdrive make these 1980s era trucks hard to live with for today’s higher highway speed limits. The first modification should be installing an overdrive transmission. The best fuel economy will come when the engine is running at 1,800-2,000 rpm at your chosen cruise speed. Depending on how fast you drive, this may also require a differential gear set change too. For a fuel economy oriented 6.2L diesel, I prefer 3.42 differential gearing along with an overdrive transmission. It’s not the best choice for hauling or towing, but the fuel economy possibilities will be what you remember from your father’s Pontiac.
A few of the military electrical systems are powered by 24 volts DC. These systems include the starter, fuel injection pump solenoids, and glow system. I recommend converting these systems to their civilian 12 volts DC equivalents. Replacement parts are easily obtainable, and there’s a lot more technical assistance available if you need it in the future. Converting to all 12v systems isn’t all that difficult.
Not all auctions allow you to start the engine or test drive the vehicle. The better auctions will however offer some sort of declaration indicating what they found during a pre-auction evaluation. Otherwise, just look at appearance and whether the vehicle has been maintained.
Reliable operation of the 6.2L diesel during the winter will require the use of a block heater. I use a block heater on a timer with my 6.2/6.5 diesels whenever the overnight low dips below +20 F. I have the timer set to begin a heating cycle two hours before I need to drive the truck. Using the block heater allows the engine to start instantly, thus saving wear and tear on the batteries and starter. Plus, you begin getting heat inside the truck much sooner.
Commercial diesel fuel is regionally blended to resist clouding during the coldest winter months. This is accomplished by blending #1 petroleum diesel fuel with #2. Straight summer blend DF2 (diesel fuel #2), under just the right conditions of temperature and fuel quality, can develop wax crystals at approximately +20°F. These
crystals produce a cloudy appearance in the fuel, which accumulate in the fuel filter or on the fuel strainer in the fuel tank while the engine is running. This accumulation can get to a point of closing off the fuel supply to the engine, and the engine will stop running. Winterized #2 diesel fuel is supposed to resist clouding down to the lowest temperature expected in a given region, but fuel blending is done weeks in advance and might not be adequate for a big unexpected drop in temperature. As a precaution, all diesel owners can treat their own fuel during periods of extremely low temperatures if you don’t completely trust the winterized fuel blending at the pump. Most national brand fuel treatments can help diesel fuel resist clouding and gelling. As of the spring of 2017, I’ve driven a diesel pickup through a total of 31 cold Montana winters, and have never once experienced gelled fuel. Good luck with your truck.