Seasonal Readiness

Winter diesel season is open in the Mountain West. Colorado's cold-weather diesel specifications run October through March and are tighter on the Western Slope. The commercial vehicle chain law has been in force on I-70 since September 1. This year the cold-weather work lands on top of a tight diesel market, with temporary federal and Colorado relief that ends on different dates in December. The fundamentals have not changed: know the cloud point of what you are hauling and storing, keep water out of tanks, have chains on before the hill, and plan for a terminal or refinery problem in the coldest week.

1. WHAT CHANGES AND WHEN

• October through March: The Colorado Division of Oil and Public Safety (OPS) applies low-temperature operability (cloud point, ASTM D2500) requirements to diesel. Limits tighten through January and ease into March, and Western Colorado limits are stricter than Eastern Colorado's because of elevation. OPS allows a flash point waiver when a cloud point of -12 C (10.4 F) or lower is specified for November through March. The OPS sheet (revised Jan 11, 2021) does not publish the monthly tables; get current limits from OPS. Source: https://ops.colorado.gov/sites/ops/files/2021-01/diesel_analysis_and_specifications.pdf
• September 1 through May 31: Colorado's Commercial Vehicle Chain Law requires vehicles over 16,000 lbs combined weight to carry chains or approved alternative traction devices on I-70 from milepost 259 (Morrison) to the Utah line, whatever the weather. A tandem-drive tractor needs 4 chains, 4 AutoSocks, auto chains, sanders, or cables of 0.415 in. or larger (cables only with chains on the outer tires of one drive axle and at least four devices). Penalty: up to $500 plus a $79 surcharge; $1,000 plus a $157 surcharge if a stuck vehicle blocks the road. Source: https://csp.colorado.gov/chain-law-information
• Same season, lighter units: Service trucks and pickups under 16,001 lbs on I-70 between Dotsero (MP 133) and Morrison (MP 259) fall under the Passenger Vehicle Traction Law. Under SB25-069, a 2WD vehicle must have chains or an approved device on two drive tires when the law is active; upgraded tires alone no longer comply. Source: https://csp.colorado.gov/chain-law-information
• Wyoming: Level 1 limits restricted sections to vehicles with chains, adequate snow tires or all-wheel drive. At Level 2, commercial vehicles must chain at least two drive wheels at opposite ends of the same drive axle. Fines are $250, or $750 if the violation causes a closure. Source: https://dot.state.wy.us/home/travel/winter/chain_law.html
• Hazmat at the Divide: Loaded fuel trucks are barred from the Eisenhower-Johnson tunnels and use Loveland Pass (US 6). When the pass closes, CDOT escorts hazmat vehicles through the tunnels starting at the top of the hour and holds other traffic. Source: https://www.codot.gov/news/2025/june/loveland-pass-us6-extended-closure-due-to-mountain-slide
• Outlook: NOAA's 2026-27 Winter Outlook (Oct 15) centers on a very strong El Nino, with the best odds of above-normal temperatures in the northern Rockies, higher odds of a drier northern Mountain West, and equal chances for Intermountain West precipitation, as reported by LiveNOW from FOX. Interpretation: a warm-leaning seasonal outlook does not rule out arctic outbreaks. Set fuel specs for the coldest week, not the average. Source: https://www.livenowfox.com/news/noaa-official-us-winter-outlook

2. OPERATIONAL READINESS CHECKLIST

Dispatch

• Ask each supplier which terminals are blending #1 or additized winter diesel, starting when, and to what cloud point. Get it on the product spec sheet or bill of lading. (Interpretation)
• Build Loveland Pass closures into mountain ETAs: when the pass closes, a loaded truck waits for the next top-of-hour tunnel escort.
• Check COtrip and WYDOT road reports before releasing mountain loads, and name one person with no-go authority. (Interpretation)
• For drivers running under the national fuel HOS waiver: they carry a copy, drive no more than 16 hours in 24, and get 6 hours in the sleeper or 8 off duty each 24 hours. FMCSA gets a crash report within 2 business days. The waiver ends Dec 16 at 11:59 p.m. Source: https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/2026-09/HOS%20Waiver_Transportation%20of%20Fuel%20Waiver.pdf

Drivers

• Check chain count and type against your axle configuration now, and run a practice chain-up in the yard. Never stop in a travel lane to chain or unchain (WYDOT).
• Cab kit: spare fuel filters, an emergency de-gel product, gloves, light, and the waiver copy if used. (Interpretation)
• Report hard starts, power loss or filter restriction warnings right away, and note the last fuel stop.
• Gelled-fuel response (Interpretation): get the unit somewhere warm or apply approved heat, use a de-gel product (a preventive anti-gel will not fix fuel that has already gelled), change the filters, and keep a sample from the vehicle tank and from the tank it was fueled from.

Plants and storage

• Draw water bottoms off bulk and dispenser tanks before the first hard freeze. NREL's guidance is to keep tanks dry, sample regularly for microbes, and use a biocide where growth has been a problem. Source: https://afdc.energy.gov/files/u/publication/biodiesel_handling_use_guide.pdf
• Treat early. CHS advises moving to a seasonally enhanced blend as overnight lows approach 32 F. Each 10% of #1 diesel lowers cloud point by about 3 F. Untreated #2 can cloud at roughly 6 F to 14 F. Source: https://www.chsinc.com/news-and-stories/2025/01/10/freeze-warning
• Cold flow additives usually lower CFPP, not cloud point (NREL). Interpretation: blend them in while the fuel is still well above its cloud point, not after wax has formed.
• Store biodiesel blends at least 5 F to 10 F above their cloud point, and protect aboveground tanks, pumps and dispensers from cold and wind (NREL).
• Test cloud point and CFPP on the first winter loads and keep the results with the bills of lading.

Accounting

• Dyed diesel: set a written policy by state and channel. Federal penalty relief runs Oct 1 through Dec 31, 2026. Keep depositing and reporting section 4081 tax; IRS guidance on deferring payment and on Form 720 is still pending. Source: https://www.irs.gov/newsroom/irs-provides-dyed-diesel-fuel-relief-related-to-excise-tax-following-president-trumps-executive-order
• Review customer contracts for any cloud point or winter-spec warranty before the first cold-weather complaint. (Interpretation)
• Keep retained samples, BOLs and spec sheets organized for supplier claims and customer disputes over gelled fuel.
• Give chain-law citations, tows and escort delays their own cost codes so the season can be measured. (Interpretation)

3. REGULATORY AND SUPPLY DATES IN THE WINDOW

• Oct 1 to Dec 31, 2026: IRS dyed-diesel penalty relief (IR-2026-122, issued Oct 14). It covers federal tax only. Source: https://www.irs.gov/newsroom/irs-provides-dyed-diesel-fuel-relief-related-to-excise-tax-following-president-trumps-executive-order
• Oct 9, 2026: Colorado Executive Order D 2026 020, "Taking Action on High Gas Prices in Colorado." As reported by Denver7, it directs public safety officials not to enforce the state ban on dyed diesel on highways through the end of 2026, directs CDOT to issue permits letting fuel trucks carry more weight, and seeks an EPA waiver of reformulated gasoline rules for 2027. Order list: https://governorsoffice.colorado.gov/governor/2026-executive-orders Report: https://www.denver7.com/news/local-news/gov-jared-polis-issues-executive-order-aimed-at-high-gas-prices-in-colorado
• Through March 2027: Colorado OPS cold-weather diesel requirements.
• Dec 16, 2026, 11:59 p.m.: The FMCSA national HOS waiver for gasoline and diesel transport expires.
• May 31, 2027: Colorado's chain law season ends.
• Supply context: Wyoming Public Media reported record national diesel prices in late September, linked to Middle East conflict and refinery outages, with no terminal shortages reported in Wyoming. Source: https://891khol.org/we-cant-take-much-more-of-this-trumps-energy-crisis-hits-truck-and-tractor-across-wyoming/

4. WHAT WENT WRONG IN RECENT SEASONS

• December 2022, Commerce City: Suncor began shutting down part of Colorado's only refinery on Dec 20 in extreme cold. Fires followed on Dec 24 and Dec 27, and full restart was projected for late Q1 2023. The refinery supplies 35 to 40 percent of Colorado's gasoline, according to the Colorado Wyoming Petroleum Marketers Association. Interpretation: the coldest week is when local supply is most likely to fail, so have a second terminal and a second carrier set up before December. Source: https://cpr.org/2022/12/29/suncor-has-shut-down-colorados-only-refinery-thats-raising-concerns-about-air-quality-and-higher-gas-prices
• January 2024, Montana: Executive Order 2-2024 cited historic low temperatures, higher heating-fuel demand, delivery delays and long terminal waits, and suspended HOS limits for haulers of residential heating fuel. Source: https://www.fmcsa.dot.gov/emergency/montana-executive-order-2-2024
• 2025-26 chain season, Colorado: The State Patrol reported 2,722 commercial vehicle citations under the must-carry law. At mobile checkpoints, 9.6 percent of commercial drivers contacted were in violation. Source: https://www.truckersnews.com/news/article/15825361/colorado-state-patrol-cite-over-2700-cmv-for-mandatory-chain-law
• Fuel quality (older, but the mechanism is the same): a distributor reported fuel gelling when cloud points ran 5 F to 10 F above ideal, very waxy fuel gelling even at ideal cloud points, and finer 4-micron filters contributing. Source: https://mansfield.energy/?p=35678 (January 2018)

5. THREE DEEPER READS

• NREL, Biodiesel Handling and Use Guide, Sixth Edition. Covers cold flow, storage and tank housekeeping: https://afdc.energy.gov/files/u/publication/biodiesel_handling_use_guide.pdf
• Colorado State Patrol, chain law information. Covers equipment by axle configuration, coverage areas and penalties: https://csp.colorado.gov/chain-law-information
• Colorado OPS, Diesel Analysis and Specifications. Covers the state's seasonal cold-flow framework: https://ops.colorado.gov/sites/ops/files/2021-01/diesel_analysis_and_specifications.pdf

Not legal advice. Items marked Interpretation are operational judgment, not regulatory text; confirm applicability with the issuing agency.