By Mike McGlothlin
Winter is hard on vehicles, especially diesel-powered equipment. Not only are high compression engines more difficult to turn over in the cold, but it’s also harder for frigid engine oil to flow through them. On top of that, the fuel itself is susceptible to gelling up any time ambient temperature drops below 20 degrees F. Without question, operating a diesel vehicle in wintry conditions can be an uphill battle. Luckily, there are multiple ways to prep your diesel engine to survive—and even thrive—in the cold. From testing your batteries to properly treating the fuel in the tank, the following tips will keep your diesel running at peak performance all winterlong.
How, Why, And When Diesel Fuel Freezes
As diesel fuel freezes, the paraffin wax that’s part of its chemical makeup begins to crystalize. Often referred to as waxing or gelling, this gives the fuel a hazy appearance. As things progress (or worsen), the fuel’s cold filter plugging point (CFPP)— the temperature where diesel will no longer flow through a fuel filter due to the formation of wax crystals too big to pass through the element—is reached. This is often called “gelling up.” Depending on the fuel you buy at the pump, as well as where you live, any fuel colder than 20 degrees F is fair game for gelling up. If you live in the north, you’re well aware that sub-20-degree temps can occur every night.
Run An Anti-Gel Fuel Additive
While winter blend diesel fuel does a decent job of resisting gelling, using a proven anti-gel additive can provide added insurance and even drop your CFPP. A reputable diesel additive will disperse water without the use of alcohol, as alcohol lacks lubrication and is extremely hard on fuel hoses, pumps, and even injectors. Additionally, a creditable additive will prevent clogged fuel filters and hoses, enhance the fuel’s lubricity, stability, and detergency, and some products can even increase the fuel’s cetane number (more complete combustion and improved fuel efficiency). In extreme cold conditions, it’s advisable to add a double dose of your preferred additive to your tank.
Emergency Fuel Additives—A Different Animal
Different from daily use anti-gel diesel additives, emergency additives that are intended to thaw out gelled up fuel filters and hoses (as well as reliquefy fuel) should only be used as needed. This is because many employ harsh ingredients such as alcohol to help de-ice frozen components and fuel. As previously mentioned, alcohol is hard on injection system components and can even damage them with regular exposure. However, for diesels that live in climates where sub-zero temps aren’t out of the question, it pays to keep an emergency, thaw-out type of additive in the vehicle with you, such as Amsoil’s Diesel Recovery, Diesel Winter Rescue from Hot Shot’s Secret, or Power Service’s Diesel 911.
Only Fill Up With Winterized Or Winter Blend Diesel
To be sure, 99 out of 100 filling stations in America will have already switched over from summer blend diesel to a fuel that’s better suited for colder temperatures by the middle of October each year. However, the type of winter blend diesel you can buy may vary from region to region in the U.S. For most areas, winterized #2 diesel, which has been treated to a cold weather additive package, suffices. In the extreme, northern climates (including Canada), winter blend made up of a mix of diesel #2 and kerosene may be available. When presented with the option between the two, it’s up to the end-user to make the most informed decision.
Park Indoors
006 Diesel Fuel Stabilizer Additive Gold Eagle Sta-Bil
If or whenever possible, always park indoors. Shelter has a tremendous effect on cold starts, even in non-heated spaces. If you can’t park indoors, do your best to park the vehicle out of the wind and, if equipped, utilize your block heater (more on this in a bit). If
you plan to store a diesel vehicle for the winter months, make sure to pour a stabilizing additive such as Gold Eagle’s STA-BIL diesel formula in the tank and top off the tank before parking it. The STA-BIL diesel formula reduces oxidation, demulsifies water, adds detergents, resists degradation and the formation of sludge, and preserves diesel fuel for up to 12 months.
Key Takeaways:
*Diesel fuel can begin to crystalize as soon as 20 degrees F
*Winter diesel additives can prevent clogged fuel filters
*Emergency diesel additives should only be used in a gel-up situation
*Always fill up with winter blend diesel in winter (avoid summer blend)
*When possible, park indoors
*Use your block heater (or install one)
*Load test your batteries before winter hits
*Test your glow plugs (if applicable)
*Keep a spare fuel filter in the vehicle
*If possible, switch to a lower viscosity engine oil
Use Your Block Heater
Well, it’s there for a reason… Most diesel engine block heaters warm engine coolant, which in turn heats the engine oil and makes startups much easier in cold temperatures. A warm engine places less strain on the batteries, not to mention the fact that it will build oil pressure much quicker. Many block heaters call for 1,000 watts, so they will inevitably raise the electric bill. For this reason, a lot of folks hook them up to an outdoor timer that turns the block heater on a few hours before the engine needs to be turned over. If you’re curious about the functionality of your existing block heater, it can easily be tested using a voltmeter (hint: a block heater either works, or it doesn’t).
Checking Battery Health
Screenshot
After batteries are exposed to a hot summer causing fluid evaporation and corrosion (which essentially reduces their cold cranking amps), hard-starting and/or dead-in-the-water scenarios commence the minute Old Man Winter arrives. Some key battery tips: 1) at least 12.5 to 12.6 volts should be available in the key-on position, lower than that and you’ve got a weak battery. 2) 10 volts should be on tap when cranking the engine over, and voltage should never drop below it. 3) at 10.5 volts, a 12-volt battery is technically considered fully discharged. 4) 13.5 to 14.7 volts should be available with the engine running.
Load Test Your Batteries
It’s vital to note that a good battery can mask the symptoms of a dying one. In multiple battery systems, it’s difficult to be sure which unit is the problem child—or if both (or all of them) are. This is why you should load test each battery. For vehicles that sit for days or even weeks between usage, consider adding a battery tender to your arsenal. Last but not least, if the health of your batteries checks out but voltage isn’t rising back to the aforementioned 13.5 to 14.7 volts in a timely manner following startup, take a look at the alternator. The alternator’s primary job is to recharge the batteries and do so quickly.
Test Your Glow Plugs (If Applicable)
Glow plugs are a vital starting aid in many diesel applications, among them are the popular Power Stroke V-8 line offered in ’94.5-present Ford ¾-ton and larger pickup trucks, as well as the 6.6L Duramax V-8 found in ’01-present GM HD trucks. Your glow plug system can be checked by accessing and unplugging the glow plug harness and, using an ohm meter, touching one lead to ground and the other to each individual glow plug lead. A resistance reading of less than six ohms almost always indicates a glow plug in proper working order. On some engines, it’s up to the oil temperature sensor to command whether or not the glow plug relay (or module) gets energized, which makes it ideal to perform a glow plug test on a cold engine.
Fuel Filters, Fuel Filters, Fuel Filters!
It goes without saying that there is a much higher volume of fuel stored in your vehicle’s fuel tank than its fuel filter—which is one reason why the fuel filter is a common point for gelling on a diesel engine. Additionally, your fuel filter likely already has a small amount of water in it, and guess what H2O wants to do when temperatures drop below freezing… Before winter hits, install a new fuel filter (or filters). A high-mile, aged, and partially plugged fuel filter is hardly detectable, and a winter deep freeze may send it over the edge. And in addition to starting with a fresh fuel filter, it behooves you to keep a spare in the cab, just in case.
Lower Viscosity Engine Oil
First and foremost, always check your specific engine manufacturer’s recommended engine oil and weights and follow them accordingly. If you can, switching to a thinner (lighter weight) engine oil, as it will flow more freely in frigid temperatures. This means cold starts are made easier, and the oil will provide more protection during startup in the form of sufficient and timely oil pressure. As an example, when ambient temps dip as low as -20 degrees F, Ford recommends 5W-40 for the 6.7L Power Stroke as opposed to the 10W-30 suggested under normal usage (0 to 100 degrees F). For temps below -20* F, Ford lists 0W-30 as an option.
