this is my first winter with my 93 7.3. untill this morning the coldest morning we had was 20 degrees. i've never had a problem starting. this morning the temp was about 2 degrees. i had a heck of a time starting the truck. run no additives so i figured the fuel had gelled. i gave it a shot of starting fluid and eventually got it started. it ran like crap and i had to give it about 1/4 throttle for about 20 minutes before it would idle on it's own. i limped to the parts store and bought some anti gell stuff made by whoever makse diesel kleen. put that in and topped off the tank hoping it would raise the fuel temp. finally it started running right after about 45 minutes.
i get to work and 2 people tell me that the new low sulfur diesel doesn't gell untill -20 but the internet says it accually gells sooner than the old diesel. whatever that temp is.
i guess my question is when does diesel gell? was my fuel gelled this morning? i've got additive in it now. it's likely gonna be cold again tomorrow and if i can't start my truck i'll need to make arrangements for a ride.

 

I belive regular #2 fuel gells around 15 degrees, but I'm not sure.

 

if you can plug it in and make sure all your glowplugs are working

 

That would be my guess also.

 

found this and thought it would be helpful
What temperature does diesel start gelling up? - Yahoo! Answers

 

Diesel has two ratings that apply here.
CP is the fuel cloud point where the wax starts to be visable, the fuel looks cloudy.
CFPP cold filter plug point is where enough wax crystals have condensed out of the fuel that it will plug the filter.

Almost all fuel distributors blend the fuel in winter, either #1 diesel or kerosene that it should be able to handle below the normal winter temps.

Where you can get into trouble is if the temp takes a sudden plunge well below the season average temp.
If you see this in the forcast, get one of the many fuel treatments in your tank before the temp goes down.

Not sure how much the ULSD has affected the CP or CFPP, but in the old days the CP of unblended #2 was about 40 degrees.
By the low 30's you were at CFPP.

Today I would say you should be good down to close to zero with pump fuel in colder climates since they normally blend the fuel.
How can you tell if the fuel is blended?
If you keep fuel mileage, as they start blending the fuel the MPG always drops.
You will also notice less power since the fuel is blended with lighter fuels which contain less BTU's per gallon.

I did a Google search of Diesel CFPP and came up with over 15,000 articles.
Looks like they have added another term WDO Wax Drop Out to ULSD which can happen above the cloud point.

Here is that link,
CFPP vs CP

When in doubt, use antigell formulations to lower CFPP.