Been running stanadyne with no problems. Even when it was -6°F here.

Basically ulsd waxes at a higher temp then lsd and once the wax does drop out, its a bitch to get it to reabsorb back into the fuel. Also says that most aftermarket fuel enhancers have no affect on gel point of the ulsd.

Here's something interesting I read on a different forum....

I copied and pasted it from there:

It is your 2 micron FASS (or whatever brand) filter. That's the problem. I see it every winter with my customers. Diesel fuel contains paraffin (petroleum wax). It gels in the cold, right? So we dose our fuel with anti-gel and deicers. You have to understand what an anti-gel does and more importantly what it doesn't do.

Anti-gels act as a copolymer in diesel fuel on the paraffin molecules. When untreated fuel cools, the paraffin molecules crystalize and begin to bond together, forming a gel. Anti-gel additives bond with the paraffin molecules and prevent the paraffin molecules from bonding together. If you keep the paraffin molecules separate, you won't get a gel or wax disintegration in the fuel. Preventing the paraffin molecules from bonding together ensures that they will still pass through the fuel filter, effectively reducing the cold filter plugging point (most gel issues really manifest on the fuel filter face, not in the tank).

That all sounds great, but remember what micron rating most fuel filters have. Most fuel filters are between 7 and 15 micron. You are filtering at 2 micron. This is where the problem arises because of what anti-gels (copolymers) do not do.

While anti-gels DO prevent paraffin molecules from bonding, anti-gel DO NOT prevent paraffin molecues from crystalizing. It is important to know that anti-gels reduce the cold filter plugging point of your fuel, but they do not change the cloud point of the fuel. Fuel "clouds" when the paraffin molecules begin to crystalize. Even treated fuel will cloud, usually at the same exact temperature as untreated fuel.

So the problem is that you are forcing paraffin molecules that are crystalized (clouded) through a very very fine 2 micron filter. A human hair is 70 to 75 micron in diameter. So this is why every winter I see gel issues, fuel pressure issues, and fuel starvation issues with trucks that run a 2 micron fuel filter. No matter how much anti-gel you feed that truck, it won't affect the cloud point of the fuel.

The best solution is to find a 5 to 10 micron fuel filter to run on your FASS (or whatever) in the winter. I have a FASS 95 pump, no filters. I'm pushing through my factory fuel filter housing on my '02 with a 7 micron Donaldson filter. I've never had a gel issue.

So it isn't an issue of the additive being mixed properly. It is an issue of anti-gels (copolymers) having no affect on the cloud point of diesel fuel and you're forcing paraffin crystals (clouded fuel) through a 2 micron filter. To keep your crystal formations smaller and to try to coax fuel through a 2 micron filter, doubling up on your anti-gel MAY help because it will help ensure that you have enough copolymer molecules on board to properly encounter as many paraffin molecules as possible. 2 micron filters are sensitive and you'll likely need to treat heavier in cold weather or find a coarser fuel filter.

Here ya go Frone ...

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Ultra-Low Sulfur Diesel Fuel Cold Weather Information

The Ultra-Low Sulfur Diesel (ULSD (S-15)) that we started to receive in mid 2006 has shown some dramatically different cold weather characteristics from the earlier High Sulfur (HSD (S-5000)) and Low Sulfur Fuels (LSD (S-500)).

These new characteristics including higher temperature gelling, wax dropout, icing, and difficulty in treating have in the first year and will continue into the foreseeable future to provide some significant challenges to distributors and end users during cold weather.

Due to these new characteristics users in areas of the US where they have not seen cold weather problems in the past, are now and will continue to see serious issues with gelling, wax dropout, and icing.

Here are the main issues known today:

Wax in diesel fuels, Paraffin wax is a natural and important part of diesel fuel. This wax provides several beneficial characteristics including high energy content (Btu's), lubricity, stability, and viscosity. The negative characteristics mainly revolve around cold weather operation and include gelling and something new we refer to as wax dropout.

In HSD and LSD the wax characteristics were relatively well understood and consistent. For example the "Rule of Thumb" used for adding kerosene (#1 diesel, Jet A) to #2 fuel to lower Cold Filter Plug Point (CFPP) was that for every 10% kerosene added to #2 diesel you would lower CFPP by approximately 5°F. An example would be that a 50% blend would have improved CFPP by about 25°F.

However the new ULSD has had several important characteristics changed by the new refining processes. The catalytic cracking and hydrodesulfurization processes remove some of the wax, it alters the size and shape of the wax seed crystals in the fuel, lowers the aromatic content of the fuel, removes a significant amount of the Lubricity, and lowers the fuels ability to dissipate static electricity by as much as 100 times.

There are a number of problems with this new fuel. First, it is currently very expensive, ranging anywhere from $.30 to $1.00 more than regular kerosene, second it is not available in all areas, and third this new ULSD #1 is not as effective at lowering the Cloud Point (CP) and CFPP (gel point) of the fuel. For example; ULSD #2 when blended with 10% ULSD #1 will lower the CFPP by only 2°F or maybe 3°F. This means that a 50% blend would only improve CFPP by 10°F.

To make this problem even more difficult, many of the diesel fuel anti-gel additive products that have been on the market for last 5 to 30 years have little or no effect on ULSD. The change in fuel chemistry brought about by changes in the Catalytic Cracking processes and the addition of Hydrodesulfurization have rendered many of the most popular products nearly useless in ULSD.

There is a new cold weather problem that the industry has not adequately defined  as of today. We are calling this issue "Wax Dropout". Wax Dropout occurs when diesel fuel is "cold saturated". This where the fuel reaches a given temperature and stays at or below that temperature for a given period of time. This time period is usually between 48 and 72 hours or longer and the temperature can vary with different batches of fuel. This past winter we saw this problem at between 5°F and 10°F.

When the fuel gets to the Wax Dropout temperature, say for example 8°F and stays there for 48 to 72 hours, the wax will suddenly agglomerate and fall to the bottom of the container. This wax plugs filters and fuel lines until it is removed or until the fuel temperature is raised to a point where the fuel will reabsorb the wax.

Again there is a further complication, in that the "old" HSD and LSD wax would gradually start to reabsorb as the fuel temperature rose. With ULSD when wax dropout has occurred the wax does not begin to reabsorb until the fuel reaches fairly high temperatures, often above 40°F, 50°F or even higher. This can make the process of getting an engine with gelled fuel to run properly far more challenging than we have ever seen before.

In the fuel distribution and fleet operations businesses, we have relied on CFPP as a measure of winter fuel quality for many years. CFPP is a fairly complicated test involving using a vacuum to draw a sample of fuel through a 45 um (micron) screen within a given period of time.

When the HSD and LSD were most prevalent and most fuel filters were 10 um there was a good correlation between CFPP and the temperature at which a standard fuel filter would plug. For example you could be relatively certain that a fuel testing for CFPP of -25°F would provide trouble free operation to -15°F to -20°F.

However the relationship is much different with ULSD. A ULSD fuel testing -25°F CFPP might have filter plugging problems at between -5°F and -10°F. Also CFPP does not seem to be directly related to Wax Dropout. A fuel can test for -15°F and still have Wax Dropout at 8°F.

Furthermore, OEM engine manufacturers have changed the media size of their fuel filters. Where 10 um has been almost an industry standard, we now see 7 um, 5 um, and even 2 um filters today. This throws the whole relationship between CFPP and winter operability out the window. For example fuel that is at the CP can have filter plugging problems with a 2 um fuel filter.

The industry has not yet agreed on or developed testing methods to measure cold weather operability with the new fuels and filters.

Until such time as the industry develops a test method for determining the relationship between CFPP, PP, Wax Dropout, and filter media size for ULSD, we suggest the following: For 10 um filters; Take the midpoint between PP and CFPP, for 7 um filters, take the midpoint between PP and CFPP, then take the midpoint between that number and the original CP, for 5 um and 2 um use the CP.

 Water is more of a problem than ever before. Diesel  and biodiesel fuels hold water dissolved in them. The amount of water that ULSD is able to hold is greater than that of HSD or LSD. One of the characteristics of fuel is that its ability to hold water in solution diminishes as the temperature decreases. Fuel delivered at 70°F with 200 ppm of dissolved water will as the temperature drops begin to push that water out of the fuel into droplets. These droplets can be seen floating in the fuel and as temperatures reach and go below 32°F those droplets freeze becoming ice crystals.

As a result many of the cold weather problems where people believe they have fuel gelling problem are actually a fuel icing problem. If you have operability issues in temperatures above 0°F you should check to be sure that you aren't dealing with ice.

Customers are regularly reporting situations where they have no water in storage tanks, no water in vehicle or equipment tanks, but they constantly have water in filters and separators. This is due to dissolved water falling out of solutions.

Enertech Labs has formulated and enhanced our cold weather products such as Complete Fuel Treatment, Polar Flow, and Thaw-It to work with the new ULSD. These formulations work with HSD, LSD, and ULSD #2, #1, #4, and #6 fuels.

EnerFuel will disperse water in all fuels including biodiesel.

WOW. . .I didnt know ULSD had that much of a higher waxing point than LSD. . .I figures it would have a slightly higher point due to the refining process. .. but WOW. I also didnt know about the fuel needing to be heated to higher than 50F for it to get the wax to mix back into the fuel. . .

To these....

We say thank you

hmm this post sounds familiar  http://dodgeownerforums.com/smf/index.php?topic=4190.0  Seems like they do a pretty good job with the fuel around here.  It was -5 and my truck still started and ran fine without any treatment.  Shoulda added some anti gel for cheap insurance though.