Sommerdiesel im Winter mit Fliessverbesserer | Posts 16+

klahaui wrote:

How exactly do paraffin crystals behave in this case?

http://www.focus.de/auto/ratgeber/sicherheit/minus-20-grad-und-kaelter-wenn-eisklumpen-den-diesel-stoppen_aid_711340.html

Waiting for better weather.
However, in extreme cold temperatures of up to minus 35 degrees Celsius, even this fuel becomes viscous and clogs the fuel system. If the car is parked overnight in a still-warm garage, it may be possible to drive a few kilometers the next day before the icy wind freezes the lines. Vehicles belonging to people who park outdoors simply won't start. The best thing to do is then to tow the car to a warmer place, such as a garage or workshop, and wait for better weather. After the fuel thaws, the car is again ready for normal use.

Hi,

Bertil wrote:

Waiting for better weather. However, in extreme cold temperatures of up to minus 35 degrees Celsius, even this fuel becomes viscous and clogs the fuel system. If the car is parked overnight in a still-warm garage, it may be possible to drive a few kilometers the next day before the icy wind freezes the lines.

In my opinion, this is an exaggerated representation because the fuel from the warm tank would need to be cooled below the cloud point (CFP) on its way to the filter. Furthermore, shortly after engine start, warm diesel from the return line is often mixed with the fuel in the filter itself. Therefore, you are generally safe for a few meters after starting. Additionally, hot diesel fuel enters the tank through the return line and heats the fuel already present there. It's important to remember that when diesel fuel expands from system pressure (e.g., 1600 bar) to atmospheric pressure, it can heat up by more than 50°C.

Here's another line of reasoning that leads to the same conclusion: During development, it is required that a certain system be able to start up to a specific temperature. Let's assume that the system can still start at -28°C and does so. Once the engine is running, the engine block warms up, and warmer diesel flows into the tank. Regardless of how you argue, once the engine starts, the diesel becomes warmer. I cannot imagine that at an outside temperature of -35°C, the "warm" diesel on its way from the tank to the fuel filter would cool down so much that it completely blocks the entire line. When I remember the winter days when I had summer-grade diesel in the tank, the problem was always starting (the filter needed to be warmed with a hairdryer), never the subsequent driving.

When I remember certain cold winter days, the diesel fuel would increasingly clog the filter after a cold start due to its coagulation. You could spend the whole day stopping every 20 km to thaw it out with hot water. Nothing warms up sufficiently after starting the engine. The only solution is an electric diesel heater. I had one of those (Bosch) installed on my Passat, attached to the filter flange. It had a heating power of 120W, and the engine ran smoothly.
hg
Herbert.

What octane rating does "Sommerdiesel" have, and what happens if you use it?
Is there anything about DIN standards available as well?

Summer diesel fuel: 0°C or below.
hg
Herbert.

Nach Selbstversuch würde ich die Grenze bei -5-8 Grad ziehen. Bis -5 relativ problemlos, ab -8 eher kritisch. Everything for VP-TDI.
It can certainly look different depending on the filter used, especially with CR/PD.
For peace of mind, you can also place one or two chemical hand warmers and some tape in the glove compartment. If the diesel filter is clogged, activate the hand warmers, wrap them around the filter, wait a bit, and then continue on your way.

Quote:

Based on my own experience, I would set the limit at -5 to -8 degrees Celsius. Up to -5 is relatively easy, but above -8 it becomes more critical.

Yes? After how many attempts?
hg
Herbert.

Quote:

Based on my own experience, I would set the limit at -5 to -8 degrees Celsius. Up to -5 is relatively easy, but above -8 it becomes more critical.

Yes? After how many attempts?
hg
Herbert.

I'm going to try something next week .
The yeast improver has been ordered, and next week it will go into the cold room .
Let's see what happens.

@klahaui
Sounds good. Try using "fliessFit" and then put it in the freezer.
What are you looking for? Clear 1.5L PET bottles?
"Could you please take a picture for us showing the layering? The sediment at the bottom should be a good indicator."
It would also be interesting to see the current "autumn diesel" price for comparison.

@Herbert : es bleiben meist immer einige Kanister im Herbst übrig, die werden dann über den Winter verfeuert... PD-TDi, VP-TDi, m TDI.
I always pour it through a funnel with a fine sieve, which allows me to clearly see the changes that are happening.
Up to approximately 0 degrees Celsius, there is nothing visible. Then, you can observe how it becomes cloudy or milky. And at temperatures below -5/-8 degrees Celsius, paraffin precipitates begin to form in the sediment.
It's possible to drive the VP TDI engine smoothly even with slightly diluted diesel fuel.
After a period of very cold weather, but around 0 degrees Celsius, I had to start my Land Rover TDI. It ran for about a kilometer before the fuel filter clogged. I wrapped it with a cloth, poured hot water on it, waited for 10 minutes, and then it started working again.
"Nights with temperatures as low as -24 degrees Celsius, using a winter additive (added to the warm diesel!), and the VP TDI engine started flawlessly."
It surprised me too; I would have expected the limit to be around -15.
However, I'm not entirely sure if I didn't leave the sediment at the bottom of the canister back then, just out of caution.

So, finally, here's my feedback .

3 attempts: Summer diesel fuel (0.5L) in freezer: after 5 hours it became slightly thick and very cloudy; the next morning it was white and flaky --> impossible to use for driving.

Summer diesel with approximately 150 ml of flow improver per 200 liters; as expected, it looked better than the "normal" diesel after 5 hours, but slightly better than anticipated.
The next morning, it was also clogged here --> making it impossible to drive.

Then I had another 20 liters of diesel (and poured out 0.5 liters afterwards), and added a little bit more to it. After 5 hours, there was nothing visible, and the next morning, there was still nothing to see.
Liquid, not cloudier than before, no flakes, absolutely nothing.

The mixing ratio is indicated on the bottle, and with a ratio of approximately 1:200, you can achieve a temperature of about -22°C.
At a ratio of 1:600, temperatures as low as -7°C are still possible.

Contrary to my expectations, this stuff actually works, but it would be too expensive for me to mix in larger quantities.
250ml costs approximately €8-12.

Best regards,

Thank you for the feedback .

Conclusion: Summer diesel should still be burned starting in the spring.