What do cloud point, CFPP and pour point mean?
They are three cold-weather readings on the same fuel, and in most fuels they show up in a set order as the temperature falls. Cloud point is the temperature at which wax crystals make the fuel look cloudy. CFPP, the cold filter plugging point, is the temperature at which a fuel filter can start to plug under standard test conditions. Pour point is the temperature at which the fuel has thickened until it will no longer flow at all.
Cloud point is the most conservative of the three and pour point the least. A fuel can pass your pour-point test and still starve an engine, because the filter plugs well before the fuel stops pouring. CHS Cenex describes cloud point as the temperature “at which wax crystals begin to appear in the fuel” and CFPP as “the lowest temperature at which diesel fuel can pass through the equipment’s filtration device without problems.”
Cloud point vs CFPP: which one should I buy against?
Buy against cloud point if you want a safe margin, and against CFPP if your supplier can show you a measured value for the fuel you are actually getting. Cloud point is the earlier warning. CFPP sits below it, and the gap depends on the fuel and on whether it has been treated, so you cannot assume one from the other.
Two state rules show how regulators lean on cloud point. Alabama’s diesel rule says the cloud point “for cold weather operation is specified at 6° C above the 10th percentile minimum ambient temperatures for the area in which the fuel will be used,” and then lists those minimums month by month: October 4° C, November -3° C, December -6° C, January -7° C. Maryland’s rule takes a different route, setting one year-round cloud point limit: “-7°C (20°F) maximum.” The cold-flow limit is local, so don’t assume a national figure.
What is the difference between #1 and #2 diesel?
#1 diesel is the lighter, lower-wax grade that stays fluid in the cold. #2 is the everyday grade.
A winter blend mixes the two. Ratios here are written #2 first: 70/30 means 70% #2 and 30% #1. CHS Cenex gives a rule of thumb: “for every 10% of #1 diesel added, the fuel cloud point will generally drop by 3 degrees Fahrenheit.” The colder your region gets, the higher the share of #1 you will need.
Treat the 3-degree rule as a planning estimate, not a guarantee. The measured cloud point on the delivered product is the number that counts.
Should I blend or use a cold-flow additive?
The choice depends on how far below the cloud point you expect to go.
| Lowest expected temperature vs fuel | What to do | Cost direction |
|---|---|---|
| Comfortably above cloud point | Straight #2, no action | Lowest |
| Near or just below cloud point | Treat with a cold-flow additive (it mainly improves CFPP, not cloud point), or a light #1 blend | Modest increase |
| Well below cloud point | Heavier #1 blend, usually with additive | Higher price |
| Far below cloud point, or equipment where a plugged filter is not acceptable, such as standby generators | #1 blend plus additive, and confirm the CFPP in writing | Highest |
Treat the table as a decision aid. Your engines, filters and tank heating change the answer.
What does a winter blend cost? A worked example
A 70/30 blend costs about 30% of the #1 premium more than straight #2. The numbers below are illustrative, not customer data or a quote.
Say you order 8,000 gallons. Straight #2 is priced at $3.00 a gallon off the rack, and #1 carries a premium of $0.50 a gallon. A 70/30 blend adds 30% of $0.50, which is $0.15 a gallon, so the blend is $3.15 and the load is $25,200 instead of $24,000, or $1,200 more. If the #2 had a cloud point of 20°F, the 3-degree rule suggests the blend lands near 11°F.
Your premium will differ by market and week, so use your supplier’s current numbers; for how rack figures are reported, see OPIS rack price. For how prices differ between markets, see diesel price by region.
Also check which gallons you are billed on. A blended load still has to be measured and priced on a stated basis, and gross versus net gallons can change how many gallons you are billed for.
What should I ask my supplier in writing?
Ask for three things, and keep the answers in an email or on the quote:
- The cold-flow spec by delivery date. Cloud point or CFPP, in degrees, for each delivery window, not “winter grade.”
- Blended or treated. Is the product a #1/#2 blend (and what ratio), a #2 with additive (and which), or both? This sets what you are paying for.
- What the BOL will say. Which product and grade is listed on the bill of lading, so you can match it to what is on the ticket and in the tank.
If you are comparing offers, the same rule applies as in how to compare bulk fuel quotes: put the quotes on the same spec before you compare price.
When does the winter switch happen?
Suppliers move to winter fuel in the fall, and the switch date and blend vary by region and supplier, so ask yours when the change happens at your terminal.
For bulk tanks, timing matters, and so does how long fuel sits between deliveries: check the cold-flow spec against that interval (see bulk fuel tank size). If you plan to use additives, treat the tanks before the cold arrives, not after fuel starts to gel. The monthly minimums in a state rule like Alabama’s show how quickly the margin shrinks from October into December. Check your own region’s figures and put the switch date in the supply agreement.
How Energy Connect handles it
This post is general guidance on winter fuel specs. It does not describe any Energy Connect feature. Your cold-flow spec comes from your supplier, so settle the three questions above before the first cold delivery, and keep the answers on the quote or in the supply agreement.