How cold before winter-blend diesel gels?
 

As I was starting my 84 300SD on this extremely cold morning (-2F / -19C), I wondered at what temperature does the winter-blend diesel begin to gel?

I believe regular #2 diesel begins to gel at 28F or so, but have never heard anyone talk about the winter stuff freezing. I would think that it depends entirely on the mixture... but there must be someone out there familiar with the specs on the stuff.

BTW, my car started after two glow cycles and keeping my foot on the "accelerator". It didn't want to idle, but after keeping the RPMs at around 1000 or so for two minutes, it would grudgingly give me a rough idle.

After sitting there for 20 minutes, it sounded fine and the drive to work was uneventful.

This is the coldest morning since I bought the car two years ago. I'd wager that if it were another 10F colder it wouldn't start and I'd have to resort to plugging it in at night.

Chris Blanchard
1984 300SD 166k (starts at -2F/-19C!)

Perhaps it depends. My fuel gelled on my one time when it was around 10 degrees outside. So if yours didn't gell at -2, then maybe you got lucky. If its that cold I would treat the fuel with an anti-gell agent. It sucks getting stuck.

GregS
'84 300D
'90 300CE

Last week it was -17F in Lake Placid, New York. Waaaaay too cold to ski, but the Benz started on the first crank like it was a spring day.

I use Rotella syntheic 5w-40 with Rotella diesel winter treatment.

Winter diesel that we made at the refinery gelled at 10 F. However if you want to lower the gel point even more, try adding some kerosene (#1 Diesel) to the #2 diesel. Half and half will lower it way down there in below zero range. Fuel mileage will not be quite as good, but it sure will start much better and idle better.

My buddy's '01 TDI Bug died 75miles into his commute last week. When he left home it was 0*..... Had the car towed to a dealer, the fuel had gelled and killed it. Now he puts in Stanadyne additive like I have been telling him all along. $50 for towing and $65 for the Stealer to say "gelled fuel" would have bought an awful lot of additive....... Can't trust the pumps to have done it for you. RT

Re: How cold before winter-blend diesel gels?
 

Your question assumes that companies all act alike (which just ain't true). Even your odds of getting the same winter-blend at a single station are pretty remote--they get a tank-fill at one blend; then another tank at a different blend, and even they couldn't tell you what the resultant blend is. Well, they could, but it would take them 15 man-hours to figure it out, and they're not going to do it.

In addition, some mixes are made at the point where the pipeline dumps the fuel into the tanker truck, and the quality control isn't necessarily world quality.

I've found that the safest bet is to add anti-gel--a good dose at the beginning of the cold season, and a little bit later on for cold snaps.

question about block heater
 

I was wondering if anyone had any idea if it is harmful to keep your block heater plugged in for a long time. I havent fdriven my 350SDL in a few days and have had the block heater plugged in around the clock since it has been extremely cold here in Michigan.

Thanks,
Frank

I think the answer to this question depends on where you are buy your fuel. There are winter and summer blends of diesel fuels - summer diesel will begin to gel somewhere in the 20's while winter diesel (at least in the mid-atlantic region) is OK until around 0F. I suspect people in new england have winter fuel that is blended to withstand temps that you would normally encounter in that region.

There are lots of addivites that can easily solve this problem, I don't use additives but if I am anticipating cold starts below 10F or so I do use an antigel agent.

Tim

For some reason,

I have seen a chart on the internet, by State and month. I remember ALabama being like -6 or -7 degrees. For somereason, I don't remember it saying F or C. -6 F makes more sense being we live in the USA.


Michael

I believe it depends on what the percentage mix is used, it will vary from 100% #2 in the summer down to I believe 50/50 in the dead of winter. Seems to go in 10% increments as the season waxes and wanes. Best person to ask would be the driver delivering the fuel, or else ask the station owner/attendant where the fuel haulers originate at (usually referred to as the fuel terminal) and maybe you can find out their number and ask what the current blend is.
I believe a 50/50 (#1 and #2) mix is good for about 20 to 30 F below zero mean temp (not wind chill).

Gilly

Here is a link to an interesting article at the TDI club concerning winter fuel:

http://www.tdiclub.com/TDIFAQ/TDiFAQ-10.html

Gilly

Mercedes owners manuals used to have a chart to guide you in making your own blends if winter diesel was not available or not adequate to prevent gelling. My 1980 300 TD manual mentions using up to 50% kerosene or up to 30% regular unleaded gasoline. I don't know when they stopped, but I think newer manuals don't mention it. I wonder if they're afraid of problems due to reduced lubricity because of the thinning or because of lower lubricity of present-day diesel fuel such as "ULSD". Steve

There is no "issue" with ULSD. It's all marketing hype to sell additives.

At the refinery where I work:
3/15 to 10/14, cloud point is 20F
10/15 to 3/15, cloud point for Texas, NM, AZ, OK markets is 10F
10/15 to 3/15, cloud point for Colorado markets is 4F