Diesel Truck Winter Storage: Earl's Step by Step Guide
For diesel truck winter storage, park it with a full tank of diesel treated with stabilizer, fresh oil, a battery tender on the batteries, and tires inflated 5 to 10 pounds above normal. Keep the DEF tank partly full, because DEF freezes at 12 degrees Fahrenheit and swells about 7 percent as it freezes. In spring, check fluids and leaks, cycle the glow plugs twice, warm the engine fully, then change the fuel filter after the first tank.
- Fill the tank right up and treat it: diesel with stabilizer keeps six to twelve months, and a full tank leaves no room for moist air.
- Hook a battery tender to both batteries for the whole winter so the truck cranks like it never sat.
- Change the oil and filter before parking: used oil carries soot and acids you do not want sitting on bearings all winter.
- Keep the DEF tank partly full: DEF freezes at 12 degrees Fahrenheit and swells about 7 percent, so leave room for it to expand.
- On the spring first start, check fluids and leaks, cycle the glow plugs twice, warm the engine fully, then change the fuel filter.
Diesel truck winter storage is not complicated, but it has to be done right. Come November there is a truck in my yard that does not move again until the snow leaves. It is an old farm pickup that has slept through more winters than some mechanics have been alive, and every spring it fires like I parked it yesterday. There is no magic to it. Park it with a full tank of treated fuel, fresh oil, a battery tender on the batteries, the tires aired up a little, and the DEF tank only part full, and it will wake up in spring like it never sat. Back when I started, men put machines away for winter the same way they put up hay, with care, because spring was always going to come and ask what you did in the fall. If your diesel is going to sit from freeze up until break up, pour a coffee and let us walk through it the way I do it here in Saskatchewan.
Fill the Fuel Tank for Winter Storage
Here is the first rule and the one most folks get backwards. Park it with a full tank, not a near empty one. A half empty tank breathes in and out as the temperature swings, and every breath pulls in a little moist air. That moisture turns to condensation on the tank walls and ends up as water in your fuel, and water is where the trouble starts. Water feeds the microbes that grow in diesel, the slime some call algae, and plugged filters are usually the first thing you meet in spring.
So fill it right up at the pump on the way home. While you are fueling, add a diesel fuel stabilizer according to the bottle, and pour it in before you start pumping so the fuel mixes it through the tank on its own. Treated diesel keeps six to twelve months sitting in a truck tank, which gets most of us through the winter and then some. If your station still has winter blend fuel, that is a fine thing to store on, but a summer fill will still sit quiet through the season if it is treated and full. If you want to read more about keeping diesel happy in the cold, our winter diesel survival guide covers gelling and additives in more depth.
Fresh Oil Before the Winter Sleep
Old oil has lived a hard life. It is carrying soot and acids from combustion, and those are the things that want to sit on your bearings and cam lobes all winter long. Give the truck fresh oil and a fresh filter before you park it. Check your manual for the right grade, and run the engine a good ten minutes to get that new oil warm and circulating everywhere before you shut it down for the last time. If you want the full tour of what soot and acids do to your oil between changes, our walkthrough of how a diesel engine works covers it.
While you are under there, look the truck over the way you would look at a horse before a long trail. Check the coolant strength, top up the windshield wash, and grease anything that takes grease. Small things done in the fall save big headaches in the spring, and that has been true for every machine I have ever owned.
Battery Tender: Cheap Winter Insurance
A diesel has two batteries for a reason, and cold is hard on both of them. A battery tender, one of those small float chargers, is the cheapest friend your truck can have in winter. It pulls about an amp and costs less than a tank of fuel, and it pays for itself the first April you do not have to buy new batteries. Hook it up to both batteries and let it keep them at full charge all season. A fully charged battery starts the truck in spring and a flat one does not, and there is no shame in admitting that a five dollar cord has saved a five hundred dollar service call more than once in my life.
If you cannot plug a tender in where the truck sits, disconnect the batteries instead. Pull the negative cables off both, and give them a full charge before you reconnect in spring. A disconnected battery sitting cold holds its charge for months. A connected battery in a truck with all its little computers awake will be stone dead by February.
Keep the Tires Round Through Winter
Tires get flat spots from sitting, and a heavy diesel sits harder than most. Before you park, inflate the tires a little above what the door sticker says. Five to ten pounds over normal is plenty. Check your manual or the tire sidewall so you do not go over the maximum. That extra air helps the tire hold its shape through months of sitting still.
If the truck will be on soft ground, slide some boards under the tires. And take the load out of the bed. No point letting the springs sag all winter holding a pile of tools you will not touch until April.
DEF in Winter Storage: Leave Room to Freeze
If your truck uses diesel exhaust fluid, that clear liquid called DEF, here is the one place where full is wrong. DEF freezes at 12 degrees Fahrenheit, about 11 below zero Celsius, and that is perfectly normal. The trouble is that it swells by about 7 percent as it freezes, just like water does. A tank that is brimmed has nowhere for that swelling to go, and something expensive will give way.
So store it with the DEF tank partly full. Two thirds is a fine place to be. And never, ever add anything to the tank to melt frozen DEF. It needs to stay pure to do its job. The truck has its own heater in the DEF tank, and it will thaw the fluid on its own when you start driving again. You can read what DEF is and how it works in our glossary entry on DEF.
Keep the Critters Out
A warm engine bay is a hotel to a mouse, and mice have wrecked more wiring harnesses than rust ever did. Before you close the hood for the season, look for the signs: chewed insulation, nests in the air filter box, droppings on the cowl. Put traps or repellent around the tires and under the hood, and stuff some steel wool in the tailpipe so nothing crawls up in there. On the farm we leave the hood of stored machines propped open a few inches, since mice like dark closed spaces and hate a draft.
The Spring First Start
When the snow is gone and you are ready to wake it up, take your time. Walk around the truck first and look underneath for puddles or drips. Check the oil and the coolant. Reconnect the batteries if you pulled them, and pull the steel wool out of the tailpipe, since that is the kind of thing a man forgets exactly once.
Cycle the glow plugs twice before you crank. That is the wait to start light coming on and going off, then on and off again. It warms the cylinders properly and the truck will catch easier. Once it fires, do not rev it. Let it idle and warm up fully, and watch the gauges while you walk around it again. Then, and this is the important part, take it for a proper drive. Get it up to full operating temperature and work that old fuel through. Plan on changing the fuel filter after the first tank of stored fuel, since whatever settled over the winter is best caught by a fresh filter.
Here is the short of it. A stored diesel asks for the same things a working one does: clean fuel, clean oil, good batteries, and a little attention. Do these chores in the fall and the truck will reward you in the spring. Machines remember how they were treated. And when it fires on that first warm morning, stand there a minute and listen to the engine. It will tell you everything you need to know.
Frequently asked questions
Should I fill the fuel tank before storing a diesel for winter?
Yes. Fill it right up and add a diesel fuel stabilizer as you fuel, pouring the stabilizer in before you start pumping so it mixes through the tank. A full tank leaves little room for moist air, which is what causes condensation and water in the fuel. Treated diesel keeps six to twelve months in a parked truck, which gets most of us through the winter and then some.
Will DEF freeze in the tank while my truck sits all winter?
Yes, it will, and that is normal. DEF freezes at 12 degrees Fahrenheit, about 11 below zero Celsius, and it swells by about 7 percent as it freezes. Keep the tank partly full, around two thirds, so there is room for expansion. Never add anything to the tank to melt it. The truck's own tank heater thaws the fluid when you start driving again.
Should I start the truck every few weeks while it is stored?
You can leave it parked all winter without harm if the fuel is treated and the batteries are on a tender. If you do start it, take it for a proper drive so it reaches full operating temperature. A cold idle in the yard puts moisture in the exhaust and the oil and does more harm than good.
How long can diesel sit before going bad?
Diesel treated with a quality stabilizer stays usable for six to twelve months in a parked truck, which covers most winters. Untreated diesel starts to degrade and grow microbes much sooner once any water gets in. Always treat at fill time, and plan to burn through the stored tank early in the driving season.
Will my tires get flat spots from sitting all winter?
They can, and a heavy diesel sits harder than most vehicles. Inflate the tires 5 to 10 pounds above the pressure on the door sticker before parking, take the load out of the bed, and slide boards under the tires if the ground is soft. The flat spots usually work themselves out on the first warm drive of spring.