4 Winter Diesel Problems And how to fix them
As temperatures drop, many diesel owners notice a decline in their truck's performance. Engines take longer to start, develop a rough idle and deliver less power. Fuel consumption and soot can increase, bringing more frequent DPF regens that cold weather can make harder to complete, particularly on short trips.
During a cold snap, fuel can gel and block the filter, preventing the truck from starting or causing it to stall.1
Winter fuel can also provide less lubrication.2 Inadequate protection accelerates pump and injector wear. A high-pressure pump failure can send metal through the fuel system, damaging injectors and turning a pump replacement into a much larger repair.
Why these fuel problems become more serious in winter
Low cetane makes a cold engine harder to start
Cetane measures how readily diesel ignites after injection. The U.S. diesel specification permits a minimum of 40; Ford's 2025 F-650/F-750 manual specifies 45 or higher.3
Low cetane can be a year-round problem, but cold cylinders make delayed ignition more troublesome. The symptoms include longer cranking, rough idle, louder clatter and white smoke during warm-up.
Injector deposits worsen cold-weather combustion
During cold starts and warm-up, poor fuel spray adds to the difficulty of burning fuel cleanly. Without effective detergents, deposits can accumulate inside injectors and on their tips, disrupting fuel delivery and costing power and MPG.4
Poor combustion can also produce more soot. Winter short trips and prolonged idling may leave the exhaust too cool for the DPF to burn it off effectively: more soot entering the filter, with fewer opportunities to clear it.5
Less biodiesel in winter can mean less lubrication
Biodiesel blended into diesel fuel helps lubricate the pump and injectors, even in small concentrations.2
But biodiesel can crystallize at higher temperatures than petroleum diesel. Suppliers may therefore reduce its proportion in winter fuel to help prevent filter plugging.3
Reducing biodiesel can also reduce the lubrication it supplies. Any resulting shortfall needs to be replaced with lubricity additives. Cold-flow protection and wear protection are separate requirements.2
Winter fuel can gel during a severe cold snap
Refineries and suppliers add cold-flow improvers and adjust fuel blends for expected seasonal temperatures. A severe cold snap can exceed that protection.6
Wax crystals then collect in the filter, restricting the engine's fuel supply. Wax can block the filter while the fuel in the tank is still liquid.7
What your winter fuel needs
An effective winter treatment should improve cold ignition, keep injectors clean, maintain lubrication when fuel blends change, and add protection against filter plugging.
That takes cetane improver, detergents, a lubricity additive and anti-gel, at effective doses. The product's evidence should show what those doses achieve.6
- Problem 1Cetane improver
- Problem 2Detergents
- Problem 3Lubricity additive
- Problem 4Anti-gel
Why diesel owners choose Archoil
"Archoil is the real deal."
Diesel Power magazine, following its evaluation of an Archoil oil additive.8
"I highly recommend Archoil products."
George Swift, head mechanic at Jay Leno's Garage.
What AR6300 delivers through the winter
AR6300 Winter Diesel Treatment combines all four treatments in one bottle, added at each winter fill-up.
AR6300 raises cetane by up to eight points, helping fuel ignite sooner in a cold engine. The increase depends on the starting fuel and dose.9
ASTM D613 measures cetane using a standardized diesel test engine.11
Increase: [insert] points at [insert] oz per 10 gallons.
Laboratory: [insert name].
AR6300's detergents help maintain clean injectors and proper fuel spray during cold-weather operation. Its additional deposit-control chemistry helps remove carbon and soot deposits from the turbo and DPF and reduce regen frequency.
For heavier accumulated injector deposits, the Winter Diesel Kit below includes a concentrated initial cleaner.
AR6300's lubricity additive improves wear protection for the pump and injectors, including in winter fuels with reduced biodiesel content.
Archoil reports a 43% smaller wear scar in ASTM D6079 testing for AR6300.9 A smaller scar demonstrates better lubrication under the test conditions: not a percentage reduction in vehicle wear.
| Untreated test fuel | 615 |
|---|---|
| Test fuel treated with AR6300 | 348 |
AR6300's anti-gel helps prevent wax from blocking the fuel filter. Its published cold-filter plugging point is:
Actual protection depends on the fuel and dose. These laboratory results are not guaranteed vehicle operating temperatures.
What owners report in a cold snap
"Great product. I use it in my 3.0 diesel. My truck is parked for days when I go snowmobiling. I don't have the luxury of plugging the heater in, and I have peace of mind knowing my fuel won't gel at even -30°F."
John E., AR6300 customer
After treating his 2000 Jetta diesel with AR6300, Peter F. reported:
"And then going through a below zero snap I went to start the car and it started right up."
Peter F., AR6300 customer
Customer reviews. Individual results vary.
Be prepared. AR6300 needs to be in the tank before the cold arrives. Its anti-gel helps stop wax from blocking the filter, but it cannot clear a filter that has already plugged. Start treating at your next fill-up, not after the truck won't start.
Product image
AR6300_Cut-out.png (loads on the live site)
AR6300 Winter Diesel Treatment
These figures use the standard dose. Add AR6300 before cold-flow problems develop, following the label and your vehicle's fuel guidance.
Kit image
WDK png (loads on the live site)
Winter Diesel Kit
Includes AR6400-D for a concentrated one-tank injector clean and AR6300 for ongoing winter treatment.
Archoil reports a 7% fuel-economy improvement in testing with AR6400-D.10 This result applies to the deep cleaner; individual results depend on the vehicle's condition and use. Follow each product's dosing instructions.
For every diesel: Suitable for diesel vehicles, including high-pressure common-rail systems.
100% Money-Back Guarantee. Return the product for a refund if you are dissatisfied. Archoil provides a prepaid shipping label for returns within 30 days of purchase. Free shipping on either option within the contiguous United States.
Using AR6300
Can I use AR6300 in my truck?
Yes. AR6300 is suitable for all diesel vehicles and equipment, including high-pressure common rail systems: Power Stroke, Cummins, Duramax, European diesel cars and SUVs, and light-duty through Class 8 trucks. It can be used in pre-emissions, emissions-equipped and deleted engines, and is compatible with ULSD, renewable diesel and biodiesel blends.
How much do I add?
The standard dose is 1.5 oz per 10 gallons. Follow the label's instructions.
Do I still use AR6500?
Use AR6300 instead during winter. Switch back to AR6500 when anti-gel protection is no longer needed.
How does the deep cleaner fit in?
Use AR6400-D periodically for accumulated deposits, following its separate dosing instructions. It does not replace AR6300's cold-flow protection during winter.
Fuel treatment does not repair mechanical faults or replace filter maintenance and the operating conditions required for DPF regeneration.7
Sources
- CHS Inc. Prepare diesel equipment for winter conditions. chsinc.com
- U.S. Department of Energy, Alternative Fuels Data Center. Biodiesel benefits and considerations. afdc.energy.gov
- U.S. Department of Energy, Alternative Fuels Data Center. Biodiesel Handling and Use Guide (PDF). afdc.energy.gov
- SAE International. A Study of Diesel Fuel Injector Deposit Effects on Power and Fuel Economy Performance, paper 2017-01-0803. saemobilus.sae.org
- Ford Motor Company. Diesel owner's manual. fordservicecontent.com
- ExxonMobil. Diesel fuel additive considerations. exxonmobil.com
- Ford Motor Company. Diesel owner's manual. fordservicecontent.com
- Diesel Power magazine evaluation of Archoil. archoil.com
- Archoil. Why diesels struggle in winter (AR6300 cetane and ASTM D6079 results). archoil.com
- Archoil. AR6400-D Diesel Fuel System Cleaner. archoil.com
- ASTM International. D613, Standard Test Method for Cetane Number of Diesel Fuel Oil. store.astm.org